I feel that this is the most commonly misunderstood thing about evolution by laypeople.

'evolving' as a verb is incredibly misleading. There is no active process that is 'evolving'. The body didn't 'realize' that this was useful so it kept it. There was no 'success'. We're merely looking at survival bias.

When scientists say that X is probably because of evolution, they don't really explain how X happened. Just a random genetic copying error, not anything exciting. Instead, they are saying that 'not X' has disappeared because those individuals had a higher chance to die before reproducing.