What Did We Really Learn About the Space Jockey?

Ridley Scott said in many interviews that the goal of Promotheus was to learn more about the Space Jockey from the original Alien. If this was the entire goal of the film then why does it seem like most of the people who saw the movie still know next to nothing about him? It seems like we still do not know what the Space Jockey was doing with the Alien egg cargo, what his civilization is like, how he died etc... It seems all we learn about the Space Jockey/Engineer in Promotheus is that they visited Earth and may have spawned human life on the planet and now want to destroy us. It is like the character is still a giant question mark and the entire two hours of Promotheus do little to flesh out his back-story and leave the audience more confused than they were when they left the theater after seeing the original Alien in 1979. So after all is said and done in Promotheus, what has Ridley really told us about our old friend the Space Jockey? And if the entire goal of the film was to explore this one character how could things have veered off course so catastrophically?