I'd say my scenario is less far-fetched than the mythicists' scenario but the mythicists have not presented a scenario, not even a single one. Sammy Chrestus had a following in Rome, but Paul pretended they were worshiping his guy, Sammy Christ. Two centuries later, Jews that hated Sammy changed his name to "Yeshu the Bastard" as an insult. Josephus had mentioned Sammy's brother James, but the revisionists rounded up all copies of Josephus' book and penciled in "Yeshu" over "Sammy." Is that what mythicists believe? Unlikely, but you wouldn't know it from this thread.
If I were to offer my explanation for the existence of the gospels and their general protagonist I would go back to GMark and find it as Huller has, a statement on the Jewish condition at the time. It's a story meant to illustrate, teach, explain, convince, etc. The characters and events are symbolic but understood by those who heard it. It's hardly a story about a preacher being killed by Romans.
I for example didn't know that competing Jewish sects and theologians were so prominent at the time. That's important to know. It lets me understand that at the time there was a very big difference between being anti-jewish and anti-semitic. I think your details offered re historicity of the protagonist don't appreciate the historical reality that existed at the time.
And it of course could be my literary background, reading too many novels, finding symbolism, etc. But I know that's what writers do. Their narratives are not unlike great paintings, something that happens over years. So I see GMark as a story that evolved and can appreciate what I see as symbolism and arguments about Jewish theology, not a story about a preacher. Quite frankly the bit of literature iss too polished to be just about that. Do you really think that Hemingway wrote
Old Man and the Sea to tell us a story about an old fisherman?