just to clear a few things up for you, theres a couple Aliens vs Pred books out. This movie was a loose rendition of the first book: Prey. The book takes place many years in the future on a different planet, but the same ideas are there. Even in the book, the Preds are impressed with one of the human females and take her in as one them. More importantly, the book opens a curtain on the Preds a little bit, and about their civilization. As the movie kind of touched on, predators are a warrior race who's lives revovle around hunting. In the book, they drop alien eggs on the planet and fight the hatchlings, so it was kind of cool how in the movie they had their own living baby factory. But basically they fight shit to proove they're worthy to the elder preds.
it was still stupid though, a pred should be able to take out 1-2 aliens with its bare hands, but the shoulder cannnon is majorly badass