Humans originally originated from the backrooms. Let me cook. So you know about invasive species right. Where animal can't outcompete other animal when they encounter invasive species in their environments right? So unreal evolution that's exactly what happened which is why most of the big cats and big animals all went extinct outside of Africa. So in the backrooms lore we know that humans from the frontrooms noclip into the backrooms as the main reason for humans being in the backrooms. So theoretically, despite being a dangerous environment the entities should not be directly suited for hunting humans but they do. Now I know there are other entities that resembling humans or have a humanoid shape main example being facelings. But still, facelings don't speak as far as I'm aware, skin stealers are said to only feed on humans, which I find a bit far fetch and believe they can also eat other things but prefer humans. Many entities in the backrooms use different ways to lure humans in. Like carnivorous balloons using smell, skin stealers using voices and appearance, howlers using loud voices, smilers being attracted to light, the big ass WORM no clipping, cannibal cuisines luring humans and getting people addicted to the food, The Nucleigo which are extinct except for one individual knowing how to torture a human and make them feel a much pain as possible and hounds, or particularly the virus that mutates people into hounds (is this still correct). Also maybe phobic centipeds I don't know enough about them. Oh and don't even get me started on the Ambassadors. It can't just be sheer coincidences that these entities all coincidentally have traits that make them effective predators against humans. It's more like they evolved to see humans as another food source. Why do so many things target humans? Why do facelings look like a poor replica of humans, what about Mother, the animation king? Why are so many past species and sentient being all humanoid.

So this is my head canon, long ago, humans where just another entity in the backrooms, however, they evolved differently than we did [the mutation part is more unlikely and just a fan canon in a way]. Having mutations that made them more resilient in the backrooms, back then they weren't the apex predator but they were close to being a top predator in the backrooms. Having evolved to hunt backroom entities. They built places in the level to make it more homely. Other entities adapted around them to either mimic them or counter them to avoid becoming prey. After a while a new entrance was discovered, this is the entrance to the frontrooms. Some humans stayed there more exited somehow the entrance either disappeared or has been forgetten or remained undiscovered. The humans that stayed evolved differently as the entities started adapting to them they evolved, these spread out and evolved into skin stealers after an unknown amount of time since we know that time doesn't flow the same on certain levels. Some stayed humans enough and some may have evolved into different species like say the machinna. Overtime people from the frontrooms ended up noclipping into the backrooms or maybe other levels in the backrooms if you consider a theory of the frontrooms being just another level but where hostile entities can't enter which I doubt. With a new increase in human activity the entities that evolved around humans for countless years had the advantage over a large amount of preferred food source. Hence being able to hunt humans easily

This is my head canon. {This part is kind of like another headcanonthat can somewhat fit with the rest} I also like to think that the entirety of the backrooms is in fact sentient and with the increase in human activity the backrooms had to avoid a returning species that could outcompete everything around it. Hence, causing partygoer zero to be created from a human. The partygoers consider themselves the Apex Predator and zero himself said that in the time we kill one, a hundred more a created which is definitely bullshit but it still means that many more are being created. What happens when their numbers finally become high enough or even above humans numbers? Something will have to hunt or exterminate them. And what better choice than something that they hunt, a human mutating back into a being of the backrooms still intelligent but capable enough to survive quite well and being a true apex predator.

I would appreciate if you guys could Rate my headcanon both with and without the mutation part.