the brilliance of peer review is it relies on educated experts experiencing the very human feeling that the only thing better than proving that you are right about things is proving other people are wrong about things.
So when, say, a doctor does a study and discovers, idk, something new about how cells react to a certain medicine, that doctor submits it to a peer-reviewed publication, which means a bunch of other doctors go over those findings with a magnifying glass hoping like hell to find evidence that the first doctor was an idiot who missed something and is actually very wrong.
And THAT, my friends, is why we believe things that pass peer-review. Because of all the things you can trust about people, one of the things you can trust most is that they will try like hell to prove anyone saying some smart shit they didn’t think of first themselves is actually incorrect.
So every time a scientist discovers something that is accepted as true, it means like a hundred other scientists did their best to prove that scientist was wrong first. And that’s how peer review helps us trust the things we learn.