The android in Alien
is a villain in the sense that he tries to kill the human protagonist Ripley. Of course, he is only following his programming by the EVIL COMPANY
In Aliens the android Bishop reveals himself to be a hero
despite the continued sinister designs of the EVIL COMPANY
Two different directors explain why there is not a consistent theme concerning "man and his machine" in the two films. Scott is more cerebral than the ripping yarn spinner Cameron.
The next two films in the series are not, IMO, worthy of consideration.
, (IMO the best of the Alien
films) you will find what you are looking for:
David the android and his deeds are the responsibility (ultimately) of his human creators.
The Xenomorph, on the other hand, is the responsibility of the alien race that, seemingly, engineered humanity and then decided to destroy it. Although biological, it is not less a "construction" than the human created androids.
We find, disappointingly IMO, in Alien Requiem
that both constructs (machine and biological) combine to annihilate the race that gave birth to humanity. David is the engineer, the xenomorphs are his tools. The idea that the advanced aliens are destroyed by their own creations is not necessarily disappointing (although hackneyed) but the ease with which the annihilation takes place is not credible. After all, the pale-skinned giant in Prometheus
at least wrestles with the creature that kills him.
After the first two films, the movies in this series suffer from a need to perpetuate their lucrative run.
Personally, I am rather tired of the "lone warrior woman defeats the last alien killer" plot feature of these films. I enjoy creative repetition in movies that take themselves less seriously (e.g. the Die Hard series) but the Alien series (directed by Scott) aspires to a loftier place.
Try actually watching the films and then coming to your own conclusions.