Can evolution still work once there are 8 billion people on earth?

Like imagine one baby is born in America with a useful adaption. It now has to survive many generations to keep replicating to try and reach a volume that is significant in a population of 330 million. Like that would take many thousands of years and by that time so many other things would have changed and technology will have moved so far that it will now be in a totally different environment and may no longer be useful.

I can see it working well in small jungle tribes and small civilizations becuase it can become significant in not that many generations. But now when people hardly have any kids and the populations are so stupidly high nothing can get ahead before the world changes.

Is evolution still working, does anyone know?