Humans continue to evolve, but will remain one species for quite some time.
Genetic mutations happen all the time. Modern humans already almost a foot taller than 300 years ago. Europeans had developed resistance to plague by 1600, while Native Americans did not. But it did not make them into new species.
New species appears when mutations go so far that new species can't cross-breed with old species. For this to happen, "new species" needs to be isolated from an old one for many generations. And this is not possible in modern human society.