Dragon Break happens.
Also, the question was what race the DB on the wall is. The fact that the DB has been depicted as a male Nord in the trailers AND the intro, makes it an easy guess.
If You really think the canon Dragoborn is a Nord just because the Dragonborn in the trailers is a Nord, does that also means he is a vampire? Since that same Nord is decipted with vampiric eyes in the Dawnguard DLC?
The Dragonborn, as well as the previous Elder Scrolls heroes, has no specific race or gender or class.
From the Nerevarine wikia page:
"Former employee Michael Kirkbride later stated about the quote, "That line was a mistake a designer made in haste. Consider it a glitch." "