You guys are aware that Superman is always handsome and white, right? Unless it's Calvin Ellis.
And he's always raised on Earth and still a metaphor for an immigrant. He's here illegally, and he learns that he's adopted, and has to grow up knowing he's different than anyone else even if he can "pass" for a normal white dude. His being white doesn't change that metaphor, it can also extend to closeted LGBT individuals who are pressured into "blending in" with "normal" society.
Wonder Woman is in more than just BvS. She's relateable to those who didn't grow up in a "traditional nuclear family" home, has an idealistic if naive world view that's going to be challenged by reality and the struggle to hold onto your goodness and love in the face of it, and losing a loved one through unnatural means/violence (Antiope and Steve).
How effective the films are in executing these ideas is another debate, but complaints about relatability are far from the major concern. And the wider belief Marvel's heroes are more relateable than the DC heroes even in the comics has always been BS. The Marvel heroes are just as larger than life, they just also have more melodrama injected into their lives. With the more nuanced character writing starting in the Bronze Age forward (and even the archetypes the older DC comics hit upon, particularly with Superman and Wonder Woman, are very complex), and cross pollination of creators, it's become even more of a fallacy.