Above we have a rather interesting (and thankfully rather short) infographic from Harrison Desnmore about pretty much all the kinds of time travels you see in movies. Did you time traveling actions make history the way it’s always been? Did they screw up time and reality itself? Or did you create an entirely new universe based on your f-ing around in the past?
The middle one is what’s known as a “plot hole” in most instances, but the other two could fall under that category too if you expand on them enough. I’m of the firm belief that all time travel movies ultimately never make sense once you start trying to extrapolate them to their logical conclusion. Still, this is all enough to make your brain hurt for a while.
Not pictured: Primer, which is it’s own category that can’t even be explained by human words.