Have you read that theory by Tom Holland? To me it sounds highly plausible that Mohammad never existed.
that word is a title not a name - a title meaning “praise worthy one”
And there is no mention of Mo or Islam during the Ummayyad Caliphate.
I am reading a book by some German historians of Islam that presents a case that early early Islam was a Arabic Christianity that was in competition with orthodox Christianity as expressed by the Eastern Roman Empire. Much of the desire to do this is political competition with the Empire. This “Arabic\Christian” pre-Islam in its effort to create distinction from Eastern Christianity over time moved further and further away from Eastern Christian doctrines. It also argues that the name Mohammend is derived from messenger and was used originally as a term for Christ. As the separation increased the term “mohammed” anthromorphized into a human being. (Not literally !). A mythology then grew up around this person. The separation continued until it was a complete separate religion.