I also dont like the idea of God being bacteria...
But Goo could certainly be something Engineers found
somewhere in their Eden (perhaps it was guarded by that
first xenolike entity) and some of them used it to create life
sacrificing themselves for that cause and others used it for
their selfish intentions... and then something happened to them.
Goo is more similar to Eitir
than pure organic mutagen, accelerant or
some microorganism... https://en.wikipedia.org/wiki/Eitr
Ridley spoke about goo in directors commentary, he compared it to ebola saying that Engineers made it...
I never liked that explanation. He even spoke about ceiling mural... he said it depicts some kind of self sacrificing
of that humanoid figure in order to complete the last phase of that "dangerous creation" as Ridley described it.