That is a fair ommision to point out, I think. The Inquisition is as varied in it's staff as humanity is genetically speaking, though typically only perfect specimens at the top of any racial trait would make it. So it should seem that there would be other racial traits visiable among inquisitors. And in fluff, there is. Vast variability, but this game does not allow much character customization at all to begin with and really only gives you a character seemingly based on one of the miniatures from the table top game, which is kinda the intent, I think. This isn't meant to be a deep RPG, more of a Diablo-style romp in the Warhammer 40K universe.

To your point, in Warhammer 40K, all the racial types are generally well represented in story and lore. Mongolian Space Marines (White Scars and their Khans), for example, and Imperial Guard regiments of EVERY cultural background possible. But just like Space Hulk table top, and many computerized versions thereof, limit gameplay mainly to a single chapter of Space Marines, and often just the First Company of that chapter, aka the Deathwing, and character choice in that is so limited, this is much the same kinda thing. Character customization really isn't the point here, brutal warfare and burning heretics are the point here :P

It's 41 millenium, races we know now don't exist any more. You have 18'th Legiones Astartes that have jet black skin (Salamanders, their primarch is Vulcan)

En el universo de 40k, esto no es importante.

war is important

Inquisitor Toth from Dawn of War 1 was black and he was BADASS. Even Space Marines made way for him eventually.

Skin color does not matter to humans in 40K. Faith in the Emperor matters. (But a fully loaded bolter does not hurt...)