If you set the server config to limit one player per class, and set the max team size to like 8, you basically have a hero shooter. That's not an unusual config- some servers were just like that for years.

What's missing ? "Each class has two powers" is an extremely specific metric I don't think is a requirement for hero shooters, and even if it was you have the unique grenades on top of the more obvious "he can build a sentry, he can turn invisible".

You could maybe argue there aren't enough classes, but I don't buy that. As long as you have enough for everyone on the team to play something different, you're good. The characters in TF2 certainly have personality.

I knew someone who got really upset when I compared overwatch to TF2, but I think it was because they were emotionally invested in overwatch and felt bad when I was like "it's kind of like this much older game I like more". Saying the thing they love is kind of a knockoff made them feel bad.

Anyway. To your point. I wouldn't call tf2 a hero shooter first. It's not the best representation of the genre, probably. But to my point, I still stand by overwatch added very little on top of TF2. Most of Blizzard's changes were changes in minor detail. It's basically "more classes, fewer game modes, you can't run your own server, and we're going to try to sell you micro transactions "