>>214475779
Either:
>Engineers bioengineered the aliens and the black goo which they used.
OR
>Engineers found the aliens and refined them to make the black goo which they used.
In Prometheus they created humans and they clearly worship the alien (the mural) either because they found it or created it. Black goo appears to be refined from aliens (Alien Romulus) most likely because aliens have super stem cells which give them ultimate environmental adaptability and ability to go into many different hosts. Engineers probably used the black goo (they either found or created) to make themselves adaptable for space travel. Black goo with humans can make them into an Engineer like being.
