No, you're totally wrong about that. Most people, when left alone, tend to form kinship-based (that is, race-based) societies -- unless men with guns stop them. The fact that there are exceptions to this does not invalidate the premise, and the descendants of any mixed population eventually feel themselves to be a race and act according to Nature anyway.

Here's how you see the _really_ long term trend I am talking about (and this applies not only to humans, but to other creatures too): Once upon a time, many many millennia ago, all existing human races had a common ancestor. There were no racial differences between them then. But, since then, many, many differences have developed. They have racially diverged. This is how new species are eventually born. Evolution cannot take place without this process.