Blood and Magic
Dragonborn or Tiefling
Why not Dragonborn or Tiefling?
Dragonborn are a bestial race not suited for adventuring. Following the veiw of traditional D&D, anything dragon like or lizard like is a monster and an enemy.
Tieflings did once exist. And rumor is, they still do. However, if one were to become a player character, the entire campaign would revolve around them trying to avoid being burnt at the stake. The Church destroys them on site, and most are as evil as their diabolic blood would suggest.