These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
This theory is supported by some deleted scenes, which show that the Simon "personality" is actually a murderous demonic entity which hops from victim to victim, preying upon their weakness as a way in ("I live in the weak and the wounded"), and then using their bodies to commit murders.
However, it works just as well as a metaphor as it does literally. The movie leaves it ambiguous.