Space Jockey spoiler?

Maybe not a spoiler but... What if the SJ that we know from the original Alien is actually an alien that came from an engineer? They have already said the new aliens will be similar but much larger than the aliens we know. This would be a great twist on the space jockey that we have known for 30 years. When you think about it the SJ actually has a lot of the same characteristics as the aliens. The arms are very similar, the exoskeletal ribs, etc. There are some plot points to fill in such as the chest burster but we know from previous films that aliens will sacrifice themselves for the greater good. Just throwing that out there if it hasn't been discussed...