and his superpower is enhanced physical ability, granted really enhanced, but still not that flashy when compared to creating explosions, controlling a shadow creature, ignoring gravity, creating sticky grape balls, black holes, acid creation, and being a cute frog girl.
also his costume and appearance isn't that flashy when compared to big red white and blue ALL MIGHT, dominatrix Midnight, revealing Creaty and anybody with a quirk that changes their appearance.
Deku's most notable physical trait his his green hair spiky hair which is standard for anime heroes and his green costume.

His hair isn't even green, either; not really. I'm pretty sure that's just a stylistic choice to show light reflecting off of black hair. And even if it is green, he's not the only one with green hair. Hell, Tsu's hair is more green than his.