they're just categories people made up, in my opinion, for the sake of arguing

First time talking philosophy? ;)

In serious talk though, I think your comment is a perfect example of why they are real categories. You have firm opinions on all of them, and all of them are actual things that people have believed and do believe.

Most of the "can't know" school of agnostics aren't "can't know therefore equal odds", but closer to "the question cannot even be rationally considered, so any opinion at all is irrational".
What color was space before the big bang? If you say it was purple, I would disagree with you. If you say it's not purple I would also disagree. It's beyond just a simple agreement about a set of facts, it's a disbelief in the existence of that set of facts in the first place.