“But as dumb as it is, it's dumb very, very fast, and in the future, after it's all but wiped us out, it's dumb fast enough to be a problem.”

https://m.fanfiction.net/s/9658524/1/Branches-on-the-Tree-of...

But the movie is about a robot assassin, it came out when robotic assassins needed a background story.

Make terminator today and you don't need time travel, just Boston robotics with latex skin and a rocket launcher, I guess.

The time travel is a trope to handwave the mechanics of a movie - you want to tell a story about one character and a robot, why should the audience care? PH this human leads a resistance that's why.