There were two major incel communities, LoveShy, which started in the mid-2000s and PUAHate which adopted the Incel viewpoint in the late 00's. LoveShy was very pessimistic but never considered serious self-improvement, sort of nihilistic. PUA Hate at this point was more about becoming a Chad or at least more desirable to women. This is when you saw the Misc begin to copy them at first in a mocking way but then seriously. Even pre-ER, we've dealt with Fatrelle and the like, merely bringing up looks angers people.
Eventually the paranoia and passivity of the LoveShy community led them to become very inactive and irrelevant in the Incelosphere. PUAHate had exited its peak from 2012 but still held steady until ER happened in May 2014. A month later, SlutHate, as the name suggests, opened as an "edgy" replacement and now the focus was mostly on how they were discriminated by their looks and were seen as second-class citizens. There were some who felt that this alone led nowhere so Lookism was started but the aesthetics got lost in RPing and cryptomining from the outset. This is the part where I get hazy, I think the Reddit presence started with truecels then incels and finally here?
It appears that there have been three major communities, the first didn't leave a huge imprint but it did foreshadow today's pessimism. The second community is where most of the jargon and concepts came from. It has moved to various forums but their presence is what launched the community we're a part of today. Finally, the third is sort of a hybrid in terms of the two schools of thought. I'm privileged to have met some from the first although honestly the majority were contemptible people. Being a part of the second was really where I left a legacy at least compared to the average guy who has done fuckall with their lives. That's my "history of the incels".