I'm not sfs but I'll offer my views in case you're interested.
Firstly I don't think we can rely on Paul's lack of interest in the historical Jesus as a solid argument that there was no such person. I beleive that the lack of information in Paul's Epistles is probably partly due to there being less to the historical Jesus than there is in the Gospels and partly Paul's own focus on his visionary experience (the only way he can claim parity with the disciples).
What I think we can say about Jeus is :
1) He came from Galilee
2) He was, for a time, a follower of John the Baptist
(This is a point worth considering - although there is considerable "spin" in the Gospels they clearly state that Jesus submitted to John's Baptism - and the need for "spin" indicates it is something that is not likely to have been invented).
3) He either claimed to be the Messiah or many people - including his leading followers came to believe that he was.
4) He was executed by the Romans - crucified.
5) After his death, some of his followers had experiences that they interpreted as indicating that he was still alive.
In my opinion, this was enough for them to hold to their belief in Jesus as Messiah and the concept of "the Second Coming" was invented to explain away Jesus' failure as Messiah.