Is it simply: involuntarily celibate, or does it come with a package?
To me, “incel” has always meant someone who’s simply just celibate against their will, but it feels like the term now also implies a specific worldview or even a subculture. Does identifying as an incel automatically come with those negative beliefs around gender and society, or should those two have separate terms? Has the definition changed?"
It has always been the latter.
But the term itself implies the former
No it hasn’t, as per https://www.bbc.com/news/world-us-canada-45284455.amp
The original term inspired a new one, femcel: https://metro.co.uk/2022/03/20/2022-is-the-year-of-the-femcel-what-you-need-to-know-16308546/