Is it possible to do version control on my computer system files themselves?
Seems to me you need to use a VM.
Take snapshots and work without worries. If you mess up you just revert to your last known good snapshot
You can do this - you can version control anything... but I wouldn't recommend it (at least not with GIT/SVN/etc - perhaps there's some software designed for this purpose that I'm unaware of).
You'll be tracking version changes for tons of files, temporary, setting files, binaries, etc. Files would be changing all the time and you'd need to stay on top of commits and so forth. Instead I'd recommended just copying folders (backup), making changes, verifying your changes work, then deleting the backups.
It's very easy to overuse version control.
Having an external drive with time machine and allowing it to sync often will allow you to revert certain parts (or all) of the file system to a certain date.