This. The existence of Jesus says nothing about his divinity or the validity of Christianity. We have more evidence for the existence of Muhammad. Does that make Islam the 'correct' religion? We have even more evidence for the existence of Joseph Smith. Does that make Mormonism the 'correct' religion? We have video recordings of L. Ron Hubbard, along with many people still alive who have met him. Does that make Scientology the 'correct' religion?
Exactly. The possible existence of someone names Jesus ~2000 years ago gives zero validity to anything. But we don't even know that. It takes faith to believe in Jesus as a historical figure. There is as much evidence as for the existence of Harry Potter.