I think you’re one level too high on the scale. As I understand it, “species” is something like “lion” or “tiger,” and then “subspecies” would be distinctions within those groups. One of the notable things here is that for interspecies breeding, it works once—liger, mule, etc.—but that offspring usually isn’t fertile. Since the offspring of any of those four groups of humans you identified probably would be fertile, I assume they must be more closely related than entirely different species.
I think you’re one level too high on the scale. As I understand it, “species” is something like “lion” or “tiger,” and then “subspecies” would be distinctions within those groups. One of the notable things here is that for interspecies breeding, it works once—liger, mule, etc.—but that offspring usually isn’t fertile. Since the offspring of any of those four groups of humans you identified probably would be fertile, I assume they must be more closely related than entirely different species.