How come predator were trying to kill humans..?

I think it was that the predators are hunters (of course from the name) and they had hunted every other species or most of them and had moved on to humans. But in the first one Arnold ends up killing him. In the second one if you see on the ship at the end when Danny Glover is fighting the one there are skulls all over the ship and one is an alien skull. Then they made AVP which the way I took it was a ancient ritual for all new predators. It seemed that the temple was to lure people in and use humans as the host for aliens. Grow them and then hunt them to get an acid mark on them. Then the newest one AVP Requiem is set before all of them and thats why no one knows about them in the other ones. At least thats what Ive gotten from the movies and a friend who follows sci-fi movies. Hope this helps.