Your typical incel is that quiet guy in school with bad skin, plain clothes, and oily hair, whose only friends were the other outcasts. Like everyone else, they just wanted a normal relationship with a normal woman. It's the repeated failure to form those relationships that leads to the resentment and anger we now see. They weren’t always like that. The bitterness and hatred is a coping mechanism for their situation, not the cause of it.
Most of the people that fit your description that I knew in the 90s had relationships with other outcasts, the people they hung out with. Hell, I probably could have fit that description and had no issues dating!
'Normal women' includes all kinds of women, but the context implies that they are choosing some kind of stereotypical type of woman which is limiting their dating pool. Their bitterness and hatred comes from not changing their behavior to attract the type of women they were interested in.
I'm sure that's true in some cases, but I wouldn't generalize it as the explanation for most incel's situations that they simply had too unrealistic standards
Those might include standards, limited preferences, or an expectation that a relationship is just going to magically happen despite not doing the things that are necessary for a relationship to start.