How can I give a sound argument described here concerning racism?

This is a bit long-winded and complicated to explain but I guess as people reply I’ll fill in with more details.

Someone I know is arguing that different races around the world have pros and cons like Dungeon and Dragons stats, with nobody being overall superior.

I want to argue that this is a misconception because although clusters of population tend to live together, there are virtually no differences in the genes between ethnic groups, but rather more genetic variablity within ethnic groups. The only reason different ethnic groups appear different is because they adapted to the environment.

I argued that already but then the discussion went elsewhere. He said that since differences in height gives pros and cons, and ethnic groups have average heights, therefore these ethnic groups are therefore superior/inferior in certain physical aspects concerning their height.

I argued back that in that example, height can change with environmental/socio-economic factors (for example, when they did studies of refugees from poorer countries raising children in the USA, the USA-bred children were higher in height than their their native contemporaries)

But I was rebuttaled with the gene argument again that these phenotypic differences lead to pros and cons, and then he brought up pygmies and how they are technically inferior and I’m a bit lost into where to go from then on. It’s just hard to convey what I’m trying to say.

tl;dr – he says things like “Black people obviously run faster because of people like Usain Bolt” and I’m like “that’s because we’re biased and seeing the superficial differences.” How can I further construct an argument that this idea of races having different pros and cons is misleading?