People who wanted to get laid but weren’t always existed. The terminology is newish. Early incel forums were actually created to try and get them talking for psych research and a goal of reaching the level of social-emotional normalcy needed for successful relationships.

The researchers left after connecting the early community and it then devolved into various unhealthy things we have today. Various gamers and youtubers contributed to the devolvement into the various offshoots that made a pipeline to the alt-right.