The gospels were not written until decades after the events they depict were supposed to have happened, so they aren't contemporaneous. They are also anonymous.
"...The word is primarily used to refer to the four canonical texts: the Gospel of Matthew, Gospel of Mark, Gospel of Luke and Gospel of John, probably written between AD 65 and 80. [1][2] They appear to have been originally untitled; they were quoted anonymously in the first half of the second century (i.e. 100 - 150) but the names by which they are currently known appear suddenly around the year 180.[3]"
None of that exists for Mohammed.
And don't drag wikipedia into a discussion of Jesus. Come on.
Gospels
Yes isn’t it strange that is all we have is a 3rd or 4th copy no originals.
I often find that strange because Oral Tradition is not as reliable as written.
Even the Lord told Moses to write down the Commandments so there seems to be a conflict when we are told of various accounts.
Yet some would like one to believe that the Bible is infallible and inerrant while it resides in this temporal world.
Because of this distortion one allows stumbling blocks to be set up and the opposition can continue in half truths!
After all the first lie or half truth was told in garden of Eden which was more stable than the temporal world we reside in even in the garden of Eden the Lord was able walked with Adam and Eve.
If one ponders King Herod.
We see he has a record of Biblical evens written down on scrolls.