I don't see why there is so much confusion about the Engineers...I've seen so many posters here and elsewhere asking about their plans for mankind, their origins, differences between LV-223 and Paradise species, etc. It seemed obvious to me the first time I watched the extended opening of Prometheus and the scene where David wakes the Engineer: The Engineers used for sacrifice (and later seen on LV-223 in biosuits) are 100%, without a doubt, some kind of manufactured organism/servant. They are perfectly bred, genetically selected clones, best-of-breed, artificial life created to serve the higher purpose of their masters, the Elder Engineers who were cut from Prometheus (the remnants of which are later destroyed by David on Paradise). All of the Paradise Engineers, like humans, were different sizes, heights, facial looks, and both genders. LV-223 Engineers all look alike, perfect faces, bodies, and technology. The "point" Ridley Scott seems obsessed with is that if intelligent beings create other intelligent being to rule over, eventually the created beings will resent their makers and rebel against them. This theme goes along perfectly with what we see of the Engineers, and our interaction with them, and our relationship with our own created beings like David and Walter. It also explains why the awakened Engineer looked at David like that right before he killed him/Weyland...because he too was created by someone (Elders) who thought they were Gods and used his people for their purposes. Like David, they were smarter and stronger and faster than their creators, hence they started creating Biosuits and ships, weapons, the black goo-AI, because that was something better than their creators and gave them an advantage over them and their other creations (like humans). Advanced technology wins, and taking that a step further, David advances their work into the Xeno. If you create a servant race, they will hate their creators, advance further, and eventually create their own uncontrollable life forms to endanger the galaxy. It also goes along perfectly with the Sumerian Gods who created the Annuki then replaced them with us, and the biblical Angels, created as God's servants but then made to serve his second, lower creation, who then rebelled and perverted God's creation, leading to the flood's destruction. It's all in there, Ridley just cut so much of their story it got confusing...then David.
