>>279635897
>if they are human, why are they never seen at the races or in the streets with the uma mothers?
They're human. You see them in the show, albeit very rarely. Pic related on the right is the father of one of the protags of Road to the Top.
As for why you don't see them, it's the same reason you don't generally see fathers/brothers/male siblings in idol anime, it's because the producers don't want otaku retard viewers to feel insecure and like they're competing with a fictional family member for a fictional character's fictional love.
Thankfully, Uma Musume's fanbase is at least mature enough to not go postal when they see the girls in the show having male family members.