The dude found a copy of the script that was published but then removed.
It explains in detail what was going on. It has a lot to do with the religious convictions of the so called Engineers.
The whole movie made more sense after watching this.
This was a much better explanation...
Cliffs:
Engineers were an evolved race but couldn’t create life anymore
They were dying off
A “Deacon” was found and impregnated an Engineer which is how they began to create life again but it failed... so they used the Deacons blood to try to create life on other planets similar to theirs by using “Chosen ones”... ones that will drink the blood.
That failed everywhere but earth
Earth was the only planet similar to theirs (And humans similar to Engineers) and they would teach humans and be worshipped... but humans were barbaric, always killing each other, etc.
They left the planet to be what it will, but taught a child of their ways (Jesus).
Humans ultimately killed that child... so they basically said “fukk yall then”
In between time, they were running out of Deacon blood/Lords blood (they worshipped the deacon since it gave them the ability to recreate life), so they started making artificial blood.
Artificial blood (black goop) was fukked up so they weaponized it to try and destroy humans...
Thats pretty much all I got