I find plenty of variation among related groups within races also. Genetically different human populations do exist, even though there is a lot of overlap and diffusion. Even a family makes one. It ranges from having red hair or darker skin or various internal differences, and there is nothing immoral in acknowledgeing that. Anyone studying histology would surely give it some consideration. You seem to be confusing the cultural and historical segregation and discrimination of human populations with the science of anatomy.
Just look at how different each of us are on our external appearance, and would you not expect there to also be various internal variation? Or do you think that all of our insides are made exactly the same. Organs come in different sizes, and there are many genetic expressions that translate into someone having or not having certain chemicals made by the body, or made in different amounts. Many unique physiological traits run in the family, and just so happens that, although human populations are largely no longer isolated enough to be considered true races, there do exist distinct populations that all share similar variations to their human anatomy, that is perhaps not found in another population. Just like one family might have a common trait not found in another family. And there is nothing immoral in that, human diversity is what makes us beautiful, I think.