Word it felt like they glossed over what the purpose of the shadow/underground people were. You said you had a theory?
In the movie the way they explained it was that some group,possibly the gov. was cloning ppl.I would say that maybe this was just an experiment in Santa Cruz,but there could have been other posts around the country.IDK
So they were cloned with the plan of the underground ppl being controlled by the group/gov. and the real ppl would do what the clones did.
but the shit wasn't working.It was going the opposite way and the real ppl above were controlling the movements of the ppl below.
But the ppl below were crazy because they only had half a soul and was in a fucked up situation eating raw rabbits for food and were left abandoned
They used rabbits because rabbits A. were used for experiments and b. multiply fast
usually when they mimicked the movements from above they would be all crazy looking,but when Red danced she could really dance because she wasn't a clone.
So Red became their leader and started to teach them things and organized them.
When they kill the above world version on themselves they get a whole soul and they get all their memories and knowledge,but it's really not just the soul that makes them whole it's also environment.
If they were exposed to better things like Adelaide even with half a soul they could be a "real" person
That's also why they used I Got 5 On it,because the clones got half of the soul of the above "real" person
but there's much more