Those things don't always describe diversity. Area in size has nothing to do with diversity. You can't call a state with a million people "basically a city" while huge, sparsely populated states like Wyoming and Montana get to have a list of why they're diverse. Providence RI is one of the biggest melting pots in the country.
Mississippi is fairly split by north/south rather than other things. People on the coast are much different from the delta, and then there's Jackson. If you've been to a lot of these places, you'll know there isn't one single "vibe" that might appear in TV stereotypes.
So similar to what you said to him, a lot of places are a lot different than you might initially think, from stereotype or generalization or whatever it is.
I would tend to agree with other states right off the bat, but then I'd probably be guilty of doing what I just said. I'd probably check on some of them before I guess because I have no idea. Like Nebraska, for example. Doesn't Lincoln have a really high number of black people? I know it's a big city but it seems out of place for farmville USA in the middle of nowhere.