I have always thought that the Aliens, well the first ones introduced in 1979 were a lot more devious, and evil, yet smarter than their newer counter parts, mainly because I could imply on how powerful they were, or what they were capable of doing with strength in numbers. There were a lot more eggs in the space jockey ship than there were Xenomorph in Aliens. No they would attack advanced civilizations head on, but I always thought that they would, the original ones, try to impregnate civilians instead of advanced defenders. And let them breed and have more babies.