"What is an Alien film supposed to feel like?"
Well, this is merely my opinion. But, here goes.
Long Version: In the distant future, moderate to decently intelligent human beings on board a large ship/station (nostromo/sevastapol) or futuristic installation (not bedrock or cavemanville) encounter a dormant alien organism and become infected. They spend the entirety of the film being hunted by a rapidly evolving creature of a very hostile nature that is rarely shown. Its intelligence and movements are not shown and rarely discussed, and it avoids the light at all costs. In the style of "ten little Indians" the group of humans is whittled down to main characters, culminating in a slow-building showdown between the last human survivor or survivors and the creature itself. It is not necessary that any of the cast survives the film. Like jaws, it is the absence of the creature that creates the tension. The audience identifies with the characters, together in one room, while somewhere out there, something horrifying is building its home and thinking of ways and opportunities to violently destroy. The only A.I. present is of little to moderate use, and any hostile tendencies are quickly resolved and not the focal point of the film. It doesn't wind up fighting an upgraded version of itself (terminator) in a room full of stone and torches (scorpion king). There are no religious humanoid civilizations, no robed figures, no foliage, no planet full of questionable events and sights that are never questioned by the cast. etc. etc. It is teeth and metal and darkness.
Short Version: Well written haunted house film in space. There is no grandiose philosophical mission statement on who we are or where we are headed technologically or as a society. The characters are realistically intelligent and relatable. The film actually features the creature and it is taken seriously. It is a frighteningly dark and uncompromising depiction of violent interstellar contact with a hostile alien species, not the napoleanic aspirations of an over-eloquent and bisexual android. It is not the "David" show. It is an alien movie.
That being said, if these awful prequels must continue then I'm rooting for David and I hope he conquers the universe. Judging by what we've seen so far, the human species in these movies has become truly stupid and mean spirited, and must not be allowed to spread beyond the earth. All hail the king.