Like David says, they're all unnatural as they are. if you speak in the first person, a couple of these are possible: "I'm a country person", "I'm a small-town person". Generally you say as David suggests. Most common where I am is: "He's from the country", "He's from a small town/city". One we sometimes say here is "He's from the bush" (from a rural area), but this is very Aussie, I think.

Those are all unnatural. He's from the country. He lives in the country. He likes living in the country. He's (from, lives in, likes living in) a small town. Some people do use labels like country boy/country girl/small town girl/city boy/city girl but it's pretty casual and moreover could be taken the wrong way. I wouldn't recommend it. Also, someone can just say something like "I'm country" but it's an adjective.