You're just falling back to a biological argument and ignoring the social one.
Is isn't exactly rocket science to state that this is a black person:
Or that this is a white person:
The existence of edge cases where populations converge or the existence of 'mixed race' people doesn't confuse that. The existence of say albinos among black people doesn't confuse that, the genetic diversity within Africa doesn't confuse that, the fact that Aboriginal Australians also have dark skin doesn't confuse that...
Trying to ignore or trivialise the existence of 'race' socially simply because it would be difficult/unclear where to draw the lines from a biological perspective is silly. Trying to equate differences in skin colour with differences in eye colour or hair type is also silly.
Is isn't exactly rocket science to state that this is a black person:
Or that this is a white person:
The existence of edge cases where populations converge or the existence of 'mixed race' people doesn't confuse that. The existence of say albinos among black people doesn't confuse that, the genetic diversity within Africa doesn't confuse that, the fact that Aboriginal Australians also have dark skin doesn't confuse that...
Trying to ignore or trivialise the existence of 'race' socially simply because it would be difficult/unclear where to draw the lines from a biological perspective is silly. Trying to equate differences in skin colour with differences in eye colour or hair type is also silly.