It was passed down by humans, but it came from God. I don’t see why that would inherently discredit God’s existence or that Christianity is or at least could be true in principle.
The historical accounts of Jesus are not fairy tales. Historians don’t dispute that Jesus of Nazareth was a real person that really existed. It’s just that some people disregard the historical accounts that claim and confirm Jesus’ deity.
The historical evidence and some of the physical evidence such as the shroud of Turin is actually quite substantial. People as yourself are free to not be persuaded, of course, but to claim it’s all based on blind faith is not really true.
I’m not trying to convert you. If you looked at the evidence deeply and can’t get behind the God of the Bible, then that’s fine.