Sure, it dosen't take much imagination to come up with any number of possible theories and rationalisations, but that's all they'll be.
The biggest problem here is there's no
answer to who
the Space Jockeys
are & where
come from that would please everybody
If a 5th ALIEN
film came out explaining those things, a third of the fans would be pleased & satisfied, a third pissed-off & disappointed, & the last 3rd in the middle.
To quote a poster from an ALIENS
forum talking about the mysteries of the xenomorphs, the SJs & their Derelict:
“Some of life's mysteries are best left unsolved.”
I couldn't agree more.