We see exactly how the Koran plagiarized the pre existing text. Much of the mythology has been changed to meet new cultural needs. These traditions were spreading all over the lands on what you call a prophet, would have had access to this previous theology and mythology.
https://en.wikipedia.org/wiki/Islamic_mythology
Islam incorporates many Biblical events and heroes into its own mythology.
I have read all your words. It shows no knowledge of credible history as taught in universities world wide. It is theological in nature.
It factually does not hold any historical credibility over text written decades after the events. And it has no credibility after plagiarizing the religion of Israel hundreds of years after the fact.
Not a single credible historian or scholar in the whole world uses the Koran as a credible historical source when dealing with biblical history, and most view it simply as plagiarizing the earlier biblical text you denounce as not credible.
Can you answer why no credible historians use your book for real history, regarding Jesus or the bible??????????????????????????????