You obviously have no knowledge whatsoever of the authorship of the Bible. Only the 2 books by Luke, Luke and Acts, might possibly have been written by someone who was not personally aquainted with Jesus.
I don't believe Mark was a direct eyewitness. Wasn't he brought into the Church by Peter?
Yet his Gospel was said to have been written between 55 and 70 A.D.
None of the gospels mentions the destruction of the temple and the Romans destroying Jerusalem in A.D. 70. That was a pretty big deal. This suggests that the Gospels were all finished before 70 A.D.