You are correct, however adaptation is part of evolution. Adaptation takes place generation by generation, while evolution takes thousands upon thousands of years. When a species adapts over and over again, it will eventually get to a point that the current “adaptation” displays very little similarities to the “original”; that’s when it becomes evolution. (Speciation)
It’s estimated there were about 50,000 homo Erectus on earth, compared to the billions of humans we have now. Suffice to say, the big difference between homo sapien and Erectus is that we stand up a little straighter, and we are much smarter. Even now our “intelligence” is expanding our population. People are living longer. Impotent people are having sex, infertile people are having kids. We are still an extremely fragile species, physically, however we are at this point consistently smart enough to survive