The Space Jockey is in fact an engineer...

I strongly believe that Engineer hierarchy consists of a matriarch and a patriarch. A King and Queen so to speak. OR maybe the Queen runs the show. At the same time, I still believe that  the Engineers have evolved to the point where sex is no longer needed, so they may have evolved to no longer have sex organs and other than a slight variance in physical stature, there really is no difference in a "male" or "female" Engineer. Unless there is only ONE "female" Engineer and she has EVOLVED to be the master PROGENITOR. She could even be a BIOMECHANCIAL womb that GROWS the Engineer "males" to be her drones.  

@ ALIEN 426

I imagine for all the great scientific conquests the Engineers have been able to achieve, DEATH is the one thing they still cannot escape. Their quest to become IMMORTAL is the ultimate goal.

@PerfectOrganism937

The idea of the Engineers achieving some kind of evolving stage where they aren't either male or female is very plausible - note that Plato once described the androgynous as a form of proto-humans. However, I do think the ones we see in the movie are actually male; we recognize them instantly as male forms, there are too much traces of it. Other possibility would be that we only saw yet traditionally masculine groups: "religious" (the first group - the Priests in many religions are only male) and military.

The idea of their wish to achive immortal life also fits the attempt to clone/create their own - recreating something is the best way to understand its functioning in details and all that is needed to its working proccess.

That why there's a part of me that think there is two factions of Engineers. The Religious sect of Engineers use the black goo accelerant through sacrifice to create life. I wonder if the Engineers on LV-223 are a rebellious militarized faction and have weaponized the black goo to use for destruction. Who knows!

It's interesting to see the Engineer's reaction to music and literature in the deleted scenes of Prometheus. It's as if he's come upon something familiar. Perhaps the Engineers were more like us before they became so advanced. Once they started tinkering with genetic engineering they lost that part of themselves. They became almost lifeless. Maybe that's why they're given colorless skin in the movie. They're scientists playing in their laboratory. Humans are only one of their many lab rats. 

@PerfectOrganism937

Maybe two factions, or maybe different sectors of their society? Like religious, military, political, scientific, etc..!?

@Trevorl314

If the Engineers created us, we are the only known species untill now to have a Soul, consciousness, what means the possibility to express feelings and mind states through art, for example. Throughout Prometheus, we have the murals paintings, the flute, the cave paintings, things that may indicate that the Engineers, at their evolving stage, still do express themselves and share some kind of art - if it's considered to be something elevated in our society, wouldn't it be in theirs? I mean, we use to think about our "human things" - feelings, expression, possibility of creating art, as something that wouldn't exist in a high species, that would be more logical, rational, etc. But those "human things" are exactly what makes us different of the rest, and what gives us the ways to be superior to other species. Maybe the Engineers also share it, but maybe the Engineers we see in the movie are, as said before, some specific factions or from specific society sectors. For example - for a group with the function of space exploring and colonizing, would be pretty normal to have "colorless skin", living for decades, maybe centuries in space; What if there's other groups of Engineers in their home planet or other colonies?

Another possibility as to why they are so colorless is the environment they live in. If they live on a planet that has little direct sunlight they would have no need for darker skin. Also, their eyes are larger than humans, which could also be a result of their environment. Fish have larger eyes, at least some, because it allows them to draw in more light under water. 

Obviously, the murals indicate the engineers have some type of artistic flair, but not the same as humans. It's evident that their artistic expressions are entirely linked to their technology. The murals could be considered biological. The navigation system is somewhat biological. The flute was used to start the hologram system. 

My best guess is that the Engineers are more concerned with creating and destroying than anything else. Whether or not they enjoy the same pleasures that we do is yet to be seen. Of course, I'm drawing this loose conclusion based on the Engineers I see in Prometheus. They are more like fallen angels. 

A view inside the helmet. Trevorl314, great point about the local environment the Engineers live in on LV-223.

The Engineer pyramid structures provided an oasis with breathable air but the Engineers could obviously move around outside. They proved this after taking a shot from the Prometheus into the side of the juggernaut then the Engineer was able to run to find Dr. Shaw in the escape pod.

The breathable air inside the pyramid might have just been a consequence (opposed to the main purpose of the system) of the water vapor/cistern system (see below) inside the pyramid to collect large amounts of water below ground in vast containment caverns. 

You are also able to see this internal pyramid structure when Fifield sets free the spectrograph survey and the feedback goes to the pyramid scan on the hologram table in the cockpit of the Prometheus.