Board Thread:Questions and Answers/@comment-28265951-20160421125919/@comment-2112031-20180102005843

It's basically a stable time loop, in which the original timeline has been replaced by in which the original cause has disappeared. Perhaps Barry created a time remnant in the original timeline for some other unknown reason, perhaps fighting some other villain entirely.

This time remnant would then go on to become Savitar, travel back in time to fight against the original Barry and then inadvertently change his origin story in one that seems like a stable time loop, essentially causing the "original" Savitar to be replaced with a different one.