Before I get roasted, let me just start off by saying that I 150% loved the Black Panther movie and honestly feel like it's one of the best films I've ever seen. Now that that's settled, I want you to hear me out:
I don't think that T'Challa is a superhero.
I think he's a bad ass king, but he wasn't born with super human abilities. None of the previous Black Panther's were. Their abilities came from technological advancements, such as the Black Panther suit, and from consuming a concoction made from the crushed up mutuated (by the vibranium meteor) Heart-Shaped Herb after undergoing a ritual.
Now I know what you're thinking: But none of the other superheroes like Hulk, Spider-Man or Iron Man, for example, were born with "super" abilities, they all gained them throughout their lives. Which is true, but they gained their abilities during incidents, such as, radiation exposure, or bites/attacks by an animal with radiation exposure. Thus, completely altering their DNA and turning them into these people with superhuman abilities that they can't really get rid of (though, everyone has their Kryptonite).
Iron Man, on the other hand, is more like the Black Panther. His powers come from the technology and adaptations he creates for his suit. Iron Man never ate an exposed apple or something; he's just hella smart (not as smart as Shuri, though).
I'm open to believing that T'Challa is the modernized version of a superhero. I just feel like he's not a superhero in the "traditional" sense. By "traditional" sense, I mean that superheroes don't usually pass down their "powers" and abilities from person to person. A ritual is not undergone to allow people that "have been deemed worthy" to become a "superhero". All of the Black Panther's powers come from technology, a ritual and consuming a plant. There can even be two Black Panther's at a time, which we see at one point. The original comic series does mention that during the ritual the Black Panther god, Bast, can deem the "chosen one" as "unworthy" to receive the powers and refuse to allow them to live through the ritual (which consists of being buried alive and hallucinating).
I guess I'm just not really used to the idea of a superhero being able to pass down their "powers" from person to person, in a sense. And while I don't believe that T'Challa or Killmonger (once he gains the Black Panther powers) can truly be classified as a superhero or supervillian, I do 100% believe that T'Challa is a hero. And isn't that all that matters?