So I was watching Alien

Kinda see what your saying;

I've always thought the first alien was the most mechanical looking, with the sequels making them more and more into flesh like bug creatures. The first one had metal looking tubes running all over while as the creatures in alien resurrection and avp barely keep this feature.

I know what you mean. But I noticed that the Xeno in the first, though true about the metal tubes, seemed more organic. This supports the idea about Xenos being bio-mechanical. As for later generation Xenos, it might be due to the species evolving further from their original selves. If the Queen in AvP was bred in a human host, then the resulting Drone would have turned out skeletal. Just like the Queen in Aliens.

I went back and watched them you seem right because the drones in avp look a whole more like warriors than drones.You might be right and you have to remeber how they set up the movies.The alien saga was supposed to be last but came first.Shorty after predator came out and was told in story line between 1980-2010 counting predators they were supossed to stop at predator 2 but made another.And avp and avpr were supposed to be in this time.So considering the graphics that were in 1979 the movies might be diffrently made plus the avp saga was made with a diffrent directer so they might have made changes.

I had noticed this also. I hope your right about it being more primitive.

Different hosts.

The original Giger Alien was carrying DNA from the Space Jockey hence the more bio-mechanical look to it.

The further the franchise progressed, the more different the looks altered in regards to the Xenomorphs, as there was more human DNA saturation.

The xenos from Alien and Aliens are quite akin in style, and i still think the difference in the domes look is based on the Aliens' xenomorphs beeing older and more mature. I'd call them "one family".

About the xenos from the other movies - the Alien³ creature doesen't count, it's wasn't even born out of a human, and maybe even not from a "normal" facehugger if this "queen facehugger" theory is right.
The beasts from Alien 4 were different too, not because of their hosts but because they descended from a queen contaminated with human DNA due to the cloning process.
And the xenos from AvP 1... well, i heard a rumour that they've been genetically modified too, by the yautja, which could explain their absurdly short evolving time from embryo to fully-grown xenomorph. Sure, the preds don't want to wait too long for their prey to be ready for the hunt. Anyway, if that's true, the aliens from AvP 1 aren't original aliens too.

And about AvP2... yeah well i'm just preteding this movie never happened, my amusement for spinning theories to explain inconsistency errors ends there.

Then mebber how would u explain the implanted facehugger to the yautja?Because im pretty sure it was hours before the infestation and yes ik that the predalien would have to have more time to grow.

Then mebber how would u explain the implanted facehugger to the yautja?Because im pretty sure it was hours before the infestation and yes ik that the predalien would have to have more time to grow.

It could be that they just change from generation. Or since that xenomorphs aquire the same abilities and looks as the creature the face hugger attached to. [If you see Aliens 3 you'll see the runner is a regular xenomorph that just came from a dog rather then a human.] It could be that the face huggers could have laid the eggs in diffrent race's of humans causeing them to look diffrent. Or they just came up with more ideas to make the xenomorphs look better in the movies and so they just added the looks in.