I agree there are interesting historical and literary connections between religious myths.

But I wouldn't say it's moot whether Jesus was historical. Even if Christianity doesn't add much that's original or unique in terms of the content of its theology, it surely matters whether literalistic Christianity amounts to the greatest fraud or blunder ever perpetrated in human history, no? It matters whether billions of Christians have been woefully, embarrassingly wrong about their deepest beliefs, and whether their religion (which externalized and concentrated salvific divinity in a nonexistent Jesus) was only an exoteric delusion.