The basic head looks humanoid to me, but a little biomechanical in looks (going from the Giant Head statue). Due to the chair the Space Jockey was in, the Engineer(s) may or may not have a snake-like tail for movement, or be severely atrophied waist-down (if theyre this great Bio-Visier, they dont really need "that part" anymore anyways, I would think).
Some have said the face of the Giant Head (which is bald and has ears, fact), looks like Giger's Harkonnen baby-face statue design. Some have also said it has the dome eyes like the original design of the xeno. It also clearly has wire-like veins across its surface from screencaps.
This is important if its true the Giant Head is a statue of the Engineer(s). They would look the same, which would be a pretty creepy 8ft animatronic