[Luvian]

Hunters, not warriors, they have no interest in a war with humanity, which is why they hide from Humans.

Humans can declare war to the Predators and try to fight them. The Aliens can't really, they just mostly kill what get in their way.

Aliens are pretty much to the limit of their evolution. They won't really change anymore. Sure, they might mix with another specy and create some powerfull Aliens, but nothing that could protect them from an orbital attack. They also can't do as much destruction as human weapons, like Nuclear Missile in the present, and the more sophisticated weaponry of the humans of Alien 2.

We know that the only real edge the Predators have is their technological advance. The human can learn from them, the Aliens can't. So the Human are the real menace. Aliens are powerfull preys. Human are potential rivals.

An Alien colony is rather easy to destroy, if you don't mind the destruction it will cause.