Copernicus
Industrial Grade Linguist
I voted the "likely not exist" option, but that is not necessarily to deny that there might have been one or more actual people whose existence contributed to the legend. Maybe Paul really did meet James, the brother of a man who was executed by the Roman or Jewish authorities for some offense. Or maybe it was a woman whose gender got modified by sexist male chauvinists. Jesus stories were rife in the 1st and 2nd centuries, so there were lots of embellishments in the oral tradition. The orthodox movement cherry-picked a few stories that promoted the historicist position, but those could have been apocryphal. People love to tell stories, and cult movements are especially susceptible to making stuff up that confirms what they want to believe. So, even if there were some actual historical antecedents to the legend, what we have in modern times is probably a collection of myths that started at least two millennia ago and burgeoned into a very complex oral tradition. That is, what we can now say we know of the historical figure is largely fictional.