You demonstrate the problem of time travel in fiction. Cyberdyne sends a terminator back in time to kill Sarah Conner in order to prevent the existence of the guy that will eventually defeat Cyberdyne. But if the terminator were successful, John Conner would never exist and wouldn’t end up defeating Cyberdyne and therefore Cyberdyne would have no reason to send a terminator back in time to kill Sarah Conner.
Right. This is why I prefer T1, because the time travel makes sense - it’s single-timeline, closed-loop, no-paradox travel. Skynet was unaware that it worked like that and hoped they’d change the past rather than cause it to happen.
All the sequels (including T2, which I do love) fuck this up by implying (or outright stating) that time travel can change things, and it’s rarely clear if it creates new timelines/parallel universes or changes the existing timeline.
This is actually a problem I have with Looper, specifically the scene where the guy’s past self gets tortured and he starts losing body parts as it happens. It makes no goddamn sense and contradicts time travel rules established in the film itself. The guy should just wink out of existence (if it’s single-timeline), or nothing should happen to him at all (if it’s multiple-timeline).