there are, in my view, good reasons for wondering if an historical Jesus existed at all. I don't think there's a clincher one way or the other, so I rate the question as 50-50.
I don't know how to estimate the odds.
I also don't know what qualifies as a historical Jesus. The term "historical Jesus" generally refers to the idea that a real man once existed who is the inspiration for the central character in Christianity.
To a believer, this probably refers to a person who fits the description of the Jesus of the New Testament including all of the miracles, but to the skeptic, the term is mostly understood to allow one to remove the supernatural aspects (virgin birth, changing water into wine, walking on water, resurrection, etc) and still call what remains a historical Jesus.
My question is, how much can we remove from what remains before it is no longer close enough to the character in the scriptures to be called a historical Jesus?
Let's look at two extremes:
Suppose that all naturalistic aspects of the New Testament actually occurred but one. Maybe Jesus wasn't born in Bethlehem during a census. If that fact can be disproved (and I believe it has), but all of the rest were correct, we could probably all agree that a historical Jesus actually once existed.
At the other extreme, suppose that none of the story has a historical correlate apart from the fact that one or several rabbis named Jesus existed in the first century CE. If that were the case, we could probably agree that Jesus of the New Testament was a fictional character.
The question is, just how much can we carve away from this story and still say that what remains can be considered a historical Jesus?
Suppose the story is true except for the miracles, Jesus was not born in Bethlehem, he only had eight disciples and one was named Felix, Jesus was not a carpenter, his mother was not named Mary, there was no Last Supper or betrayal by Judas, Jesus was married and had children, and the Sermon on the Mount never occurred, but the rest is historical. Is that still the Jesus of the New Testament?
I realize that there is no good answer to this question. My point is to illustrate the problem with the question. Just what do we mean by a historical Jesus?
Also, it's a moot point for the skeptic, who only cares if a demigod named Jesus once walked the earth. If the choice is between a mortal man that became legendary thanks to guys named Paul and Constantine and a myth, well, it doesn't matter which is the case.
Still, I think it's worth considering what is being discussed or claimed when the phrase
historical Jesus is used.