Some thoughts on the Engineers (Novelisation spoilers)

Been thinking about the Engineers on the world that David dropped the pathogen on. Ive made peace with myself that they are indeed Engineers even though the still shots showed them to be quite different in appearance from the Engineer look we are used to. It seems Ridley possibly was just a tad lazy with touching up there appearance, or maybe we just analyse things too much. Or both. 

There's a passage in the Novelisation from David that reads as so:

"I began to do a bit of genetic experimentation of my own. Some cross-breeding, hybridizing, what have you. I like to think that the ill-fated inhabitants of this world-the original Engineers- would gaze on my work with approval."

He calls the inhabitants of the world the "original Engineers". So are these the sort of Engineers we saw at the start of Prometheus that wear the robes etc and are a more peaceful seeming bunch than the Engineers we see on LV-223, who are possibly a military style group with their strange armour suits that looks to be part of their bodies, who deal with dangerous military assignments and wiping out/cleansing planets etc., like they were planning to do to Earth 2000ish years ago.

Were individuals plucked from these "original Engineers" on the world we see in Covenant and chosen for the much revered task of seeding planets by the Elder Engineers like we see in the Prometheus extended opening scenes?.

Any thoughts?.