You can pretend it's not up for debate but that's not reality, there are plenty of very credible academics doubt the existence of a physical person as the inspiration.

Paul doesn't even pretend to know anything about the real person so there's no reason to imagine he needed a real person to have existed. For such a significant person don't you think that the people who actually knew him would be prominent in the early church rather than totally vanishing from existence? There's only Peter that has any claim of knowing Jesus and as soon as you start to look into that you start seeing red flags.

Early church history is fascinating and you're doing yourself a great disservice to ignore the interesting side of things like where it all came from because you want to believe an easy fiction.