Cameron turned the aliens into a species. They were things not made by the hand of nature, or God let's say it that way for those who are believers.
The alien was basically an indestructible (regenerated over and over again when hurt or mutilated) machine powered by acid, created by a superior race who probably evolved too and trascended their own organic nature (this leads to the very Derelict ship), and whose sole purpose was to eradicated human beings, apparently.
The mystery of the Derelict being another biomech entity that produced the aliens (the eggs) was what truly elevated the also mystery of the alien to actual satisfying levels, not reducing the alien to a natural species similar to insects, controlled by a hive minds, regardless they are weapons or not.
Each one to their own anyway. One of the good things of the alien universe was, precisely, how open It's always been to speculation. Some of us oldest fans saw it the Giger's way to perfectly fit what the creature looked like by '79 The younger generations preferred Cameron's simple approach. Ok that's fine too I guess
Anyways, everything points out to the possibility (Scott' new lore for alien) that our "Nature Boy" David has come to stay, so..
When was the alien depicted as indestructible, or able to regenerate, or powered by acid? I never saw that in any of the movies. When was the Derelict show as being biomech? Furthermore, when was the ship show producing eggs? I think you're in la la land
The whole idea is that it is "alien" and we cannot understand the full reach of it's biomechanical nature. One of the reasons the film has inspired equal intellectual debate and the usual, is because Scott and the filmmakers included all sorts of maybes, in the details of ALIEN, so you can see it in a very straightforward manner but also interpret more. This is one of the ways its such a smart movie. There are all kinds of things in the interaction between the text of the script and the design interacting with the characters and the text, and also subtext, that add a depth to it. Scott has spoken in a good deal of detail over the years addressing this stuff. The freudian elements to Giger's work and how the Alien makes the male a female when it reproduces etc etc. The Biomechanics arent treated any differently. There are hints the Alien may be communicating with the ship and naming the computer 'Mother' is no mistake.
So the Biomechanics are just another piece of that - ambiguous AND deliberate.
The Space Jockey was supposed to be an Engineer after Prometheus, but they also LEFT SOME
ROOM to ponder here, because Shaw and the films is asking "Who made them?" It is possible to consider that the Space Jockey's are a race the Engineers modeled themselves off of, but overall if you want things to be straight forward, its an Engineer in a suit, and I do think that was intended. Although now, it seems they may change that.
"God does not build in straight lines." - Holloway
I say, beware of trying to force an animal to walk a straight line, that is meant to roam free.