The accounts of the Dragonborn vary to such a degree, the only thing we know for sure was that he saved the world. The Dragonborn has been recorded as male, female, nearly every race in Tamriel, and a member of organizations as far apart as the Dark Brotherhood to the Vigilent of Stendarr. More likely, several notorious figures of their tmr have simply been rolled into the Dragonborn over time, much like the Hero of Kvatch.