Jesus' own people apparently first wrote about him about twenty years after his death, in the Epistles of Paul. Paul recorded what was important to
him from whatever he knew, second-hand, about Jesus' life. Some years later, more conventionally biographical works were written.
The chief reason for the delay seems fairly clear. Jesus' people thought he was coming back in their lifetimes. There was no point writing things for
future generations when there weren't supposed to be any future generations.
The other use for writing is to transmit information through space. There's no evidence of any systematic networking among dispersed Christian centers
before Paul set up his network. As soon as he did, he wrote things down, business correspondence.
Nobody else wrote anything about Jesus for plausibly the same reasons that few people today write about the many and colorful traveling godmen of
India. Unless you're part of that culture, you aren't much interested in reading about magic tricks better appreciated in person. If you are both part
of that culture and literate, then maybe the itinerant godman isn't the image of your people you want to present to the rest of the world.
And recall that like the Indian godmen, the Jewish Godman spoke almost exclusively to his own co-religionists. By the time writing lives of Jesus is
being done in earnest, that religion, Second Temple Judaism, doesn't even exist anymore, because there was no longer any Second Temple.
Besides, after the first generation (the one that thought it wasn't going to die, but did), Christianity had its own living people to promote the
organization by working their own signs and wonders. For example, exorcism is very dramatic, and if it's done in Jesus' name, and it "works," then you
might believe other things about Jesus, too. (For example, you might think the first generation simply misunderstood what Jesus meant about not
dying, See John
It's a good question, then, but it just isn't a big mystery. The delay isn't so long or so unaccountable that it tells much about the historicity of
Jesus. As to the divinity or prophethood of Jesus, that's faith, and so it doesn't really matter whether anybody ever wrote anythning down about that
or not. You believe it or you don't, and there's isn't a lot more to it than that.
edit on 23-6-2012 by eight bits because: of an errant keystroke.