>>212219727Too many suits fucking with the script, to the point that it no longer really made sense.
The original idea was that the engineers were extremely long lived but had lost the ability to reproduce, so they used the goo produced by xenomorphs that they found to seed life onto new planets in an attempt to recreate themselves.
Earth was one of the planets they seeded, but humans turned out flawed, they tried to fix humans by raising a human (Jesus) on their homeworld and sending him back to teach the rest of humanity how to not be barbarous. When Jesus was crucified the engineers were furious and decided to pull the plug on Earth.
The engineer that wakes up and goes apeshit was tasked with sterilizing Earth via the black goo before an accident occurred. So to him the humans are still defective retards, and now making demands of him.
There was also some distinction between the gold/black (xeno blood) goo that seeds life, and the black (synthesized) goo that corrupts/destroys life.
The "engineer" city in Covenant was likely not the engineers, but another one of the engineer's failed attempts at recreating themselves. Though more successful than Earth.