Don't try walking on the water! There are no miracles here! The writing of the Quran was Not a miracle.

Muhammad did NOT miraculously write the Quran as an illiterate.  Muhammad had many scribes to write down his recitations.

"The scribes of Muhammad were 42 in number. `Abdallah Ibn Sarh al-`Amiri was one of them, and he was the first Quraishite among those who wrote in Mecca before he turned away from Islam. He started saying, "I used to direct Muhammad wherever I willed. He would dictate to me 'Most High, All-Wise', and I would write down 'All-Wise' only. Then he would say, 'Yes it is all the same'. On a certain occasion he said, 'Write such and such', but I wrote 'Write' only, and he said, 'Write whatever you like.'" So when this scribe exposed Muhammad, he wrote in the Qur'an, "And who does greater evil than he who forges against God a lie, or says, 'To me it has been revealed', when naught has been revealed to him." So on the day Muhammad conquered Mecca, he commanded his scribe to be killed. But the scribe fled to `Uthman Ibn `Affan, because `Uthman was his foster brother (his mother suckled `Uthman). `Uthman, therefore, kept him away from Muhammad. After the people calmed down,
`Uthman brought the scribe to Muhammad and sought protection for him. Muhammad kept silent for a long time, after which he said yes. When `Uthman had left, Muhammad said "I only kept silent so that you (the people) should kill him."

-Is the Qur'an Infallible? by `Abdallah `Abd al-Fadi, Order Number VB 4009 E, Light of Life, P.O. Box 13, A-9503 Villach, Austria. The book is availabe in English, and the original Arabic edition.

Muhammad even had help with the revelation from some of his scribes.

The reason that triggered apostasy of cAbdullâh Ibn Sâd Ibn Abî Sarh was the revelation of the verse 23:12. The following is the translation of Baidawî's report proposed by the critic:

    'To me it has been revealed', when naught has been revealed to him" refers to 'Abdullah Ibn Sâd Ibn Abi Sarh, who used to write for God's messenger. The verse (23:12) that says, "We created man of an extraction of clay" was revealed, and when Muhammad reached the part that says, "... thereafter We produced him as another creature (23:14), 'Abdullah said, "So blessed be God the fairest of creators!" in amazement at the details of man's creation. The Prophet said, "Write it down; for thus it has been revealed." 'Abdullah doubted and said, "If Muhammad is truthful then I receive the revelation as much as he does, and if he is a liar, what I said is a good as what he said."

http://www.islamic-awareness.org/Quran/Sources/Sarh/

There is a great deal of testimony to the fact that Muhammad did not write any of the Quran.

"None of these letters, agreements or books has ever been written in the Prophet's handwriting; that is to say, nowhere has it been reported that the Prophet wrote by his own hand. More important still, is the fact that there is no observed instance to indicate that the Prophet had written down a single verse of the Qur'an. "

https://www.al-islam.org/unschooled-prophet-ayatullah-murtadha-mutahhari/scribes-prophet

"After Muhammad would receive revelations he would later recite it to his companions, who also memorized it or wrote it down."

https://en.wikipedia.org/wiki/History_of_the_Quran

There are a number of testimonies to the fact that Muhammad did not write any of the Quran.

 Ibn al-Qayyim said:

The scholars of seerah (Prophet’s biography) have mentioned the names of the Sahaabah who used to write down the wahy (revelation) or the letters of the Messenger (peace and blessings of Allaah be upon him). They were: Abu Bakr al-Siddeeq, ‘Umar ibn al-Khattaab, ‘Uthmaan ibn ‘Affaan, ‘Ali ibn Abi Taalib, al-Zubayr ibn al-‘Awwaam, ‘Aamir ibn Fuhayrah,  ‘Amr ibn al-‘Aas, Ubayy ibn Ka’b, ‘Abd-Allaah ibn al-Arqam, Thaabit ibn Qays ibn Shammaas, Hanzalah ibn al-Rabee’ al-Usaydi, al-Mugheerah ibn Shu’bah, ‘Abd-Allaah ibn Rawaahah, Khaalid ibn al-Waleed, Khaalid ibn Sa’eed ibn al-‘Aas (whom it was said was the first one to write down anything for him), Mu’aawiyah ibn Abi Sufyaan and Zayd ibn Thaabit. He requested them to do that and allocated this task to them.

Zaad al-Ma’aad, 1/117

Ibn Muflih al-Hanbali said:

A group of them wrote things down for the Messenger of Allaah (peace and blessings of Allaah be upon him), including Ubayy ibn Ka’b, Zayd ibn Thaabit, ‘Ali, ‘Uthmaan, Hanzalah al-Asadi, Mu’aawiyah, and ‘Abd-Allaah ibn al-Arqam, who was his regular scribe in charge of writing and responding to letters. He was the one who wrote down all the Revelation and whom the Messenger of Allaah (peace and blessings of Allaah be upon him) commanded to learn how to write Syriac so that he could respond on his behalf to those who wrote to him in that language. So he learned it in eighteen days.

Al-Adaab al-Shar’iyyah, 2/161

And Ibn Hajar said:

Al-Qadaa’i said: Zayd ibn Thaabit used to write to the kings on his behalf, as well as writing down the revelation. And al-Zubayr and Jahm used to write down the records of zakaah.

Al-Talkhees al-Habeer, 4/346, 347

https://islamqa.info/en/20968

People wrote down the Quran on anything they could or memorized it any way they could.

NO! Again, they didn't need to write it down to preserve it, althought they did. They all completely memorized it from what they heard.
Some of them wrote it down on animal skins, others on large stones or palm leaves, because the prophet Muhammad, peace be upon him, instructed them to do so. So, they did write down what they had heard and that is Quran in written form. They all memorized the Quran for themselves and passed it down the same way they got it. The mouth to ear method of memorizing is still used the same way today for modern Muslims.

http://www.islamnewsroom.com/news-we-need/112-did-muhammad-write-the-quran

Shortly after Muhammad's death, the Quran was compiled by his companions who wrote down and memorized parts of it. See Campo, Juan E. (2009). Encyclopedia of Islam. Facts On File. pp. 570–74.
https://en.wikipedia.org/wiki/Quran#cite_note-jecampo-14

After Muhammad died, Caliph Abu Bakr ordered all people who had written pages of the Quran to compile them in one place.

The project was organized and supervised by one of the Prophet Muhammad’s key scribes, Zayd bin Thabit.

The process of compiling the Quran from these various written pages was done in four steps:

    Zayd bin Thabit verified each verse with his own memory.
    Umar ibn Al-Khattab verified each verse. Both men had memorized the entire Quran.
    Two reliable witnesses had to testify that the verses were written in the presence of the Prophet Muhammad.
    The verified written verses were collated with those from the collections of other Companions.

https://www.thoughtco.com/compilation-of-the-quran-2004545

20 years later, the Quran was compiled again.

"After ʿUmar’s death the collection was inherited by his daughter Ḥafṣah. In order to forestall divergences in the recitation of the Qurʾān, the third caliph, ʿUthmān (reigned 644–656 ce), is reported to have ordered that copies of Zayd ibn Thābit’s recension be sent to the main garrison towns of the Islamic realm and that alternative versions of scripture be burned."

https://www.britannica.com/topic/Quran

Apparently, there was something wrong with the early Qurans.

"These early synoptic Qur’ans were not preserved because the differences between them led to arguments within the early Muslim community.

"The Syrians," we are told, "contended with the `Iraqis, the former following the reading of Ubayy ibn Ka`b, the latter that of `Abd Allah ibn Mas'ud, each accusing the other of unbelief." (Labib as-Said, The Recited Koran: A History of the First Recorded Version, tr. B. Weis, et al., Princeton, New Jersey: The Darwin Press, 1975, p. 23)

The third caliph, Uthman, solved this political problem by choosing one of these collections to be the standard version for the entire Muslim community. He had the other collections destroyed.

Narrated Anas bin Malik: Hudhaifa bin Al-Yaman came to Uthman at the time when the people (Muslims) of Syria and the people of Iraq were waging war to conquer Armenia and Azarbaijan. Hudhaifa was afraid of their (the Muslims of Syria and Iraq) differences in the recitation of the Qur'an, so he said to 'Uthman, "O chief of the Believers! Save this nation before they differ about the Book (Quran) as Jews and the Christians did before." So 'Uthman sent a message to Hafsa saying, "Send us the manuscripts of the Qur'an so that we may compile the Qur'anic materials in perfect copies and return the manuscripts to you." Hafsa sent it to 'Uthman. 'Uthman then ordered Zaid bin Thabit, 'Abdullah bin Az-Zubair, Said bin Al-As and 'AbdurRahman bin Harith bin Hisham to rewrite the manuscripts in perfect copies. 'Uthman said to the three Quraishi men, "In case you disagree with Zaid bin Thabit on any point in the Qur'an, then write it in the dialect of Quraish, the Qur'an was revealed in their tongue." They did so, and when they had written many copies, 'Uthman returned the original manuscripts to Hafsa. 'Uthman sent to every Muslim province one copy of what they had copied, and ordered that all the other Qur'anic materials, whether written in fragmentary manuscripts or whole copies, be burnt. ... (Sahih al-Bukhari: vol. 6, bk. 61, no. 510) "

Reciting Oral history, stories, sayings is nothing new. People from all corners of the world have been kknown to recite very lengthy materials.

It is not a miracle that people recited the Quran or portions of it.

It is not a miracle that the Quran was written down my Muhammad, because others wrote down the Quran.

It is not a miracle that the Quran was given as a revelation to Muhammad through an angel. There was no witness to this outside of Muhammad, and anyone could say that an angel told you something and not prove it.

It is not a miracle that the Quran is eloquent. Many people make eloquent statements and that does not make their statement a miracle.

It is not a miracle that the Quran is unique. Many people make unique statements and that does not make their statement a miracle.

The Quran is not a scientific miracle. Embryology and the idea of the universe being created from one thing came thousands of years before Muhammad.  There are also scientific errors in the Quran. The Quran repeatedly says the earth is flat like a carpet. "And Allah has made the earth for you as a carpet (Qur'an 71:19)." The Quran says that bird flight is a miracle, but now we know how it is done. "Do they not look at the birds, held poised in the midst of (the air and) the sky? Nothing holds them up but (the power of) Allah. Verily in this are signs for those who believe (Qur'an 16:79)" There are many more scientific errors in the Quran.  The theory of atoms began in 440 B.C., so it is not a miracle that the Quran mentions them.

The Quran is not a miracle because of the accuracy of historical records in it.  There are many serious historical innaccuracies in the Quran. The Qur'an explicitly denies that Jesus was crucified. It claims that the Jews became so confused that they crucified somebody else instead who had the likeness of Christ. It is recorded in the Qur'an 4:15, "They slew him not nor crucified but it appeared so unto them." The crucifixion of Jesus Christ is one of the most certain facts of history. The Qur'an says that the one who picked Moses from the river was not his sister but his mother (28:6-8), and that a Samaritan was the one who molded the golden calf for the children of Israel and misguided them, and the golden calf was lowing (refer to chapter 20:85-88) though it is well-known that Samaria was not in existence at that time. The Samaritans came after the Babylonian exile. How could one of them have made the golden calf for the people of Israel?
The Quran puts Haman with Pharaoh of Egypt 1,000 years before Haman's time in Persia.  

The Quran is not a miracle because of fulfilled predictions in the Quran. The predictions of military success could be easily calculated because of their overwhelming forces at that time. There are no miracles predicted in the Quran that have come true. There are no predictions over a significant span of time that come true in the Quran.

There are no miracles in the Quran to authenticate Muhammad's message as coming from God.

There was no voice coming out of heaven approving on Muhammad or his message.

Therefore the Quran is not a miracle and it is not God's message.