REM.
We are only talking semantics here. It is obvious that even though humans are considered one species there is just as much diversity as in the animal kingdom. In the animal kingdom they would call such diversity species or breeds. Amongst humans such diversity is called races. Races are also sometimes called breeds.
The special nature of man is reason enough God made him different.
Diversity just became common among mankind as man began liberally intermarrying.
If man were the product of evolution then it should be possible to interbred with apes from whence evolution says we from. There would be these many missing links you are speaking of.
It is only because if man supposedly evolved from primitive man, primitive man should have continued to exist through different lines of descendency with that of modern man. This absence is only because the truth is God designed and created man all through the original human pair.
The assumption that members of different species within kinds not being able to interbreed is erroneous. Even though different species if of the same kind interbeeding will be possible. If the limits of a kind is reached as with lions and tiger crosses and donkeys and horses then the offspring will be sterile. They therefore are incapable of further breeding.
Zechariah