Theories on the origins and the potential power of The Aliens and The Yuatja.
My theories on the Aliens are as follows:
I think that the Aliens always inhabited LV426, but in a desolate location far away from the growing space Jockeys, and the Aliens were very small in numbers. But then the Space Jockeys started polluting the atmosphere. The Alien Queen or just The Aliens (Which ever Ridley Scott had in mind when he made the movie.) sensed this through pheromones and felt out where the source of the pollution was coming from...
I think that the "Space Jockey" ship was a way of getting the remaining Space Jockeys off of the planet. But the Aliens got to them first. They were trying to get off because the Aliens had committed genocide on almost everyone of them, with the exception of the Space Jockeys in the Ship.
My theories on the Yuatja are as follows:
The Yuatja lived on a large resourceful planet with super jungles. Due to all of the resources and their natural strength, their civilization grew fast, eventually turning into groups of Galactic Predatorial clans ruled by Elders. These Galactic Predators became very powerful, with advanced futuristic weapons.
Each one of these races could conquer Earth in deferent ways. It is hard to say which race would win if they battled each other, but the Yuatja probably would prevail over centuries of war.
But if the humans got a hold of an Alien, and then found out how to control and genetically engineered them, making them much smarter, then I think the humans would beat the Yuatja and then the Aliens would kill the humans, thus, Aliens win.
Now what are your theories.