2001 isn’t complex?
Not really. It’s a pretty straightforward story when you get past the spectacle. Really the vast majority of the movie is 2 people and a computer, not a lot of complexity there. Mythological mysteries that never get answered aren’t complexity, they’re contemplation points. To me if you want complexity you usually need to head to heist or scam movie. That’s where plots get complex. Most movies are rather linear.