I used to spend considerable time reading books that debated a reality of Jesus or a fiction come to life.
The arguments are stacked so high on both sides, with the fiction side suffering more from the fact that its advocates don't have anything at stake so they don't try as hard to extrapolate from theories and known facts.
The bottom line for me was that Paul's Christ was not ever described as a physical man who lived during his own life or just prior to it. Paul's Christ was easily a symbol for people, a myth that was magnified larger than life. And the gospels were added later to this larger-than-life myth.
In the end, I decided it doesn't really matter. If myths are based on a man or not, they are not reality. The son of God did not walk the earth and sacrifice himself for all of mankind. Miracles about Jesus are no more true than miracles about Buddha are true reality.