A boy from the future came to warn us to be prepared against a catastrophic event in our future, to stop the world from becoming the way he knew it. I suppose that would create a paradox or an alternate timeline for sure. But it could also be just the same result of a mathematic operation with the numbers arranged differently.

I suppose you're right, though. After all once I return the me outside here will practically be a me that has never been here. Just for that we're different already.