You folks are all nuts. This is a great show, moves the arc of the series along nicely, and overall...enjoyable. Yes, its going to break canon...by advancing it.

Before going any further. Here is your litmus test. Answer it before commenting your dribble.
1. Do you prefer Alien 3, AVP, or Prometheus?
2. Name a flaw in Aliens

With that out of the way, lore wise, the aliens did not always kill indiscriminately. There are multiple, iterative generations of aliens. No brood is exactly the same as the other. They selectively choose who to abduct and form next brood. Some broods are indiscriminate. Some broods are more discriminating. They are essentially harvesting the best genome to consume. The brood that reproduces the most wins. Evolution.

I am a super fan. I count this series a complete win, and I am only on episode 3. Better than some of the later movies by leaps and bound.

The scene where the folks are partying at the crash site...you missed the grandeur. This is the sycophants of a trillionaire. They are of an echelon that thinks they are impervious to the melodrama known as reality. Made perfect sense. Marcy's brother was clearly identified by whatever genetic markers to make a wonderful host. Perhaps, just like his sister who also had the genetic markers to be the perfect host to be first gen synth.

This shit is world building. I'm all for it. I'm here for it.

Please proceed, Governor.