Closer Look at the Space Jockeys from Prometheus

We've already seen what the Space Jockeys looks like before and after they get their chest ripped out by the baby aliens but what really gets me going with this whole secret mythos regarding these so-called "Engineers" happen to be their looks.

 

Now we really get to see these mysterious humanoids up close as we get treated to two images for these creatures for Ridley Scott's Prometheus. 

 

I'm still curios as to why these guys look like elephants and why were we able to see one Space Jockey during the opening act for "ALIEN" decades ago.