On a chart section spanning around 5 million years, are you asking about the millions of years where there was “all this diversity and branching” as contrasted with the last ten thousand years or so where there is less observed branching?

Around 15 branches in 5,000,000 years and 0 in the last 10,000 years seems more likely statistical than ideological to me.

If a group of humans gets isolated in an island, the moon, etc., experiences a population bottleneck and bigtime selection pressures, a new species might emerge after 500 generations (about 10,000 years).

Are you not aware of the multiple genetic bottlenecks homo sapiens have gone through?

I don't think anyone can look at the incredible diversity of humans we have now and say they're all the same species, while looking at birds or other animals and say they deserve to all be different species. One of those trains of thought are wrong, and humans seem to be the outlier.

That said, I don't want to be the one to have to tell people they're another race. I think calling all humans the same race simplifies a lot of life, and there's no reason we can't treat ourselves differently.