The Big Giant Head

exactly, I understand your idea BM but it is my belief that the giant head wasn't constructed by us, but by the Space Jockeys. Why do I think this - look at the detail on the side of the big head in the last pic you posted, it is similar in design to that seen on the outside of the derelict and the inside of the map/pilot room, thus it is my opinion that this head was constructed by the Space Jockeys, not only as a marker so that they know what samples are within the urns, but also as a greeting/confirmation to us when we discover the truth about our origins... which is what the film is supposed to be about.

the explanation I came up with as to why a Human Looking Head is that some Alien Intelligence viewed their first human space traveler as a sort of God and made it in Man's image, the man they saw first.

Time will tell, but think of it this way... We find whatever it is we find that leads us to travel to a distant planet and to that room. Once there we find a huge human head overlooking a vast amount of urns, and (presumably) an empty Space Jockey suit. We grab the Space Jockey's "helmet" and one of the urns and head back to the Prometheus. Inside the urn we find a configuration of four vials stored in some green goo. Inside each vial is genetic material for various lifeforms on earth, with one of them containing human genetic material... That's my bet. Regards other rooms, I don't think they will be shown as such, most likely inferred, for example... As the crew leave the ampule room with the "helmet" and urn they walk past a passageway leading to another room. In the mist and dust more urns/ampules can be seen on the floor, and the silhouette of a large Alien head overlooking the urns/ampules.