The homebrew tools are the same ones the devs used to add official content, so the options available are the ones used by official content. A planned homebrew tool revamp will likely expand all options, but that is going to be a big update and it is not going to be soon.
I am trying to create a Homebrew feat specifically for the Minotaur race but it's not letting me set Minotaur as a prerequisite for the Feat.
The homebrew tools are the same ones the devs used to add official content, so the options available are the ones used by official content. A planned homebrew tool revamp will likely expand all options, but that is going to be a big update and it is not going to be soon.
I feel your pain. You can't even use the base classes as prerequisites as far as I can tell.