Just going to have to wait until human towns and villages are playable to play sites in mundane worlds.
Thing is, that is unbelievably trivial to mod in, so imagining what it'd look like in hardcoded format isn't that much of a brain-melter. Lemme give some examples I've observed in the process of making a (currently unreleased) human mod, in increasing order of effort:1. Just make the dwarven civ use humans instead of dwarves. Only makes sense if you're absurdly lazy or want a low-fantasy world that still has a cave-dwelling entity as the playable civ.
2. Move the playable token from dwarves to humans. Like all non-playable civs they lack positions, so you're fucked if an invasion arrives, or you need to trade, or you want to commit justice, etc. But they're by far the most playable out of the box, especially compared to elves (no way to produce wood without more modding) or worse, KOBOLDS (your citizens get classified as pets and can't have their labors changed).
3. Give a playable version of the human civ direct equivalents to dwarven positions. Assuming you go the whole hog and replace generated non-site positions like the law-giver, the only thing you lose is flavor.
4. Mock up flavor-accurate equivalents to generated human positions. This is hard without string dumps to get an idea of what the generated positions do, and you may still have to take some guesswork for gameplay reasons or for flavor. For example, when I mocked up lords I didn't give them a dining room requirement, because lords reside in mead halls, so it'd be logical to assume the human norm is to dine with ones hearthpeople and honored guests.
5. Commit sorcery and get generated positions to behave properly in fortress mode, and actually show up as valid positions. This is basically what Toady would have to do to make option 4 occur automatically in low-fantasy worlds.