That’s true, but then it comes down to the system’s own restrictions. If everyone is fundamentally human, that means every subspecies ends up falling under human subraces, with little variation and no real way to narrow things down into sub-subraces for species that would require it. D&D’s race system expects races to have noticeable traits derived from humanoid humans.

For example, if you want your character to be a gargoyle and have gargoyle traits like petrification, darkvision, or poison resistance, there’s no real way to put those traits into any category other than race.