There are two Alien movies. Alien, and Aliens. The other alien movies are studio sh-t. And the Alien-Predator crossovers are sh-t. And unfortunately, the prequels are crossovers with the David the Android plot – which is why they’re sh-t.
So what can be done?
There are two David the Android Crossover movies in the Alien Universe. Covenant and Prometheus. The android movies violated canon and removed the mystery from the alien franchise. Discovering the engineer planet by probe woud have been better than the ‘stars’ nonsense in the cave. It would have been possible to have discover an engineer planet, while not have discovered their body form. Discovered the tech, and had the Android seek to put it to ill use, without de-mystifying the engineers. It would have been even better if the engineers were just as ignorant of the aliens as man is, and succumbed to them – discovering they were not engineers.
Scott was wrong – the alien plot line is not ‘exhausted’. Like the batman franchise, it can be re-done over and over again infinitely with different context and characters, as man discovers, tries to make use of the alien and its tech, and ends up having to destroy it over and over again.
To maintain the mythos: We do not want to know where the alien came from. It needs to be as ancient as ‘ancient gods’. The aliens are not aware of man. They don’t care about man. They are just opportunistic machines. The hand of the devil instead of the hand of god. Movies in the alien plot line (franchise) need to preserve the alienness of the most mysterious alien that we humans have been able to invent.
The studios are stupid really. Why? They don’t hire competent sci-fi writers to submit competing screenplays. They try to use screenwriters who are not masters of the subject matter, with mastery of the psyche that the subject matter incorporates.