Well, if Jesus of Nazareth factually and historically rose from the grave (which would account for the tomb bein' empty, and stuff), and His friends (who saw Him dead and buried) saw Him risen from the grave and walking, talking, and eating with them -- what's wrong with His friends telling people about this factual and historical occurrence?
I have little doubt that Jesus existed, as did the others.
Even that is not as simple as it appears. "Jesus" is simply our translation of Joseph (Y'shua), a very common Jewish name. There were several other Jesuses, before and after the time of the Jesus recorded in the Gospels. Some of these Jesuses were said to have performed miracles, raised the dead, and were crucified. How do we know that the stories about these other Jesuses were not later confused/comingled with the stories about the "real" Jesus? We don't know; the historical "evidence" is always more uncertain and incomplete than the True Believers would have you believe.
Heck, we can't even be sure we know who really wrote Shakespeare, and he is only removed 400 years from us. Don't laugh this one off: there is good evidence that Shakespeare is a pen name for someone else, but it takes a bit of time and patient scholarship to sift the evidence and to get past the prejudices ingrained by the "faith" of the dominant academic scholars, who also claim to be based on nothing but solid historical fact. "Fact" is never a sure thing when you are basing something on alleged eyewitnesses and the statements of people long dead who had motive to deceive or an ax to grind.