Oh yeah,


"Lets get off of our alien infested planets while carrying a load of ALIEN EGGS"

makes alot of sense.........

They weren't carrying Alien eggs when they were taking off, just a couple of hidden Aliens, that turned the rest of the Space Jockeys into eggs.

It still cant be proven though as we dont know how many jockeys took off in the first place.
I dont remember too too much about that part of the movie so if someone could back something up that would be apreciated.

I think it is enough to say that the world they were originally from had very different indigenous life and that the standard of organism might be completely different. There are some things in nature which overpower their prey that quickly as well, mostly diseases.