Doesn't the Quran's perfect preservation prove it is from God?
Preservation is not proof of origin, and Islam's own sources record lost verses, abrogated verses, rival codices and a caliph who burned the alternatives.
A forgery can be perfectly preserved. And Sahih al-Bukhari and Sahih Muslim record verses that were revealed and are not in the Quran today, and a standardisation that removed the other copies.
9Lo! We, even We, reveal the Reminder, and lo! We verily are its Guardian.
Quran 15:9 (Pickthall) · context
106Nothing of our revelation (even a single verse) do we abrogate or cause be forgotten, but we bring (in place) one better or the like thereof. Knowest thou not that Allah is Able to do all things?
Quran 2:106 (Pickthall) · context
Sahih al-Bukhari 4987 Summary, not a quotation
Uthman orders all other copies burned.
Read the full text on sunnah.comSahih Muslim 1452a Summary, not a quotation
Aisha on the verse of ten breast-feedings, no longer in the Quran.
Read the full text on sunnah.com