File1, file2, file_3.new, etc would be bizarrely stupid. A home rolled solution involving rsync, tar, gzip, crons or inotify would also be bizarrely stupid.
en.wikipedia.org/…/List_of_version-control_softwa… anything on that list that’s marked anything other than “active” as a more serious answer. So like DCVS, visual source safe, or bitkeeper. Anything that’s not getting bug fixes or maintenance.
Anything that doesn’t have significant enough usage to give confidence that bugs or glitches are being caught by common usage would be risky, since you don’t want to be the person to find that edge case.
There’s things other than git that aren’t wrong, but I see little compelling reason not to use the most ubiquitous tool.