Up to you
The life of Prophet Muhammad is the most detailed life reported by many historians, and compilers of hadith books, and it is a well known fact that he could neither read nor write.
The Arabs at the time were very distinguished in Arabic poetry, and they had special events were they would choose the best poems and place them in the center of Makkah (at the Ka'bah).
From all the poets of the time, there is no account whatsoever of a poem written by Muhammad, peace be upon him. And when the Arabs listened to the Qur'an, which was revealed over a period of 23 years, they had never heard anything like it before, even though they were very eloquent in the Arabic language, and some would become Muslim only by listening to a few verses from the Qur'an
As for someone else writing the Qur'an, again it was not a valid argument, as if that were the case, this assumed person having written such a magnificent book would attribute the book to himself, and become the most famous of poets, but that never was the case
The Qur'an is simply beyond human capacity, and several attempts to imitate the Qur'an throughout history have failed ...