I think anything related to culture is going to be irrelevant in a fantasy-based game that takes place on another world with its own various established culture (Demacia: Right makes Might; Noxus: Might makes Right; Piltover: Steam/Diesel/Cyberpunk Utopia; Zaun: Science without moral/ethical/legal boundaries; Ionia: East Asia anachronism; Shadow Isles: Land of the Dead; Targon/Shurima: Sun worshipping anachronism of the Middle East, but particularly Ancient Egypt); Bilgewater: Pirate Land; Freljord: Viking land)
Drawing attention to race is always a sensitive issue, and by race I'm guessing more often than not people are referring to portraying blacks. Asians have plenty of representatives (Lee Sin, Xin Zhao, Akali, Shen, Zed, Karma, Master Yi, Ahri, Syndra, Irelia, Kennen to an extent, and Yasuo) and while most of them are no longer humanoid, the Middle East also has representatives (Nasus, Renekton, Azir, Xerath, Sivir, Rek'Sai, Kassadin [maybe], Cassiopeia to an extent, Leona, Pantheon, Diana, and Malzahar). The Spanish don't really have a representation outside of maybe Twisted Fate and anyone associated with Bilgewater who isn't a fish (pirates mostly originated from the British/Spanish empire), but those are not very positive representatives or portrayals in the first place. Blacks so far have only two representatives as of this post: Ekko and Lucian.
When you go down the list, there are honestly not that many verfied white champions, either, and I've heard the argument before that this is a white dominated roster. When you remove champions explicitly from certain race-specific locations like Ionia or Shurima, who are not/no longer entirely human as well as the ones with abnormal skin colors (Soraka, Ryze (Human Ryze skin doesn't count), Brand, Elise, Evelynn, Zyra, etc), the list of verified white as the virgin snow white people is surprisingly small (Annie, Ashe, Braum, Caitlyn, Cassiopeia by origin (her sister is white, so chances are she was probably white as well), Darius, Draven, Ezreal, Fiora, Gangplank, Garen, Gragas, Graves, Janna, Jarvan IV, Jayce, Jinx, Katarina, Leblanc, Lux, Miss Fortune, Nunu, Quinn, Riven, Sejuani, Singed, Sion based on his human concept art, Sona, Swain, Talon, Taric, Tryndamere, Twisted Fate, Udyr, Urgot if he was not a mass of dead flesh, Vayne, Vi, Vladimir, Zilean). Almost 40 champions verified white, which as of this post is just slightly more than 30% of the total champions in the game. I don't really look at race, and I feel that if race dominates design, then it's a bad design, and most people (read: most people who aren't artists or designers and a few who are) won't get that. Lucian's identity isn't dominated by the fact that he was the first black character; his identity is an undead-killing widow who wants revenge for the death of his wife. There was an old post about someone's character concept for a weighty woman; his character design and personality put too much emphasis on her size, so as other summoners pointed out, it was a bad design. Braum's the size of a mountain, but his personality and his lines never really draws attention to it (aside from carrying around a door that probably weighs as much as an SUV).
