I think it would be better put that we
cannot evolve anymore.
If you're aiming for inaccuracy, that would be better.
We certainly can
still evolve. We don't need to evolve at the moment for reasons you mentioned in your post, but change our environment significantly, and we will
evolve (or go extinct).
People tend to think of this in the short-term, but evolution takes a very, very long time. Just look at the history