How much do Americans actually pay for healthcare?

Hey all, I'm British so I don't really know the ins and outs of the US healthcare system. Apologies for asking what is probably a rather simple question.

So like most of you, I see many posts and gofundmes about people having astronomically high medical bills. Most recently, someone having a $27k bill even after his death.

However, I have an American friend who is quick to point out that apparently nobody actually pays those bills. They're just some elaborate dance between insurance companies and hospitals. If you don't have insurance, the cost is lower or removed entirely. Supposedly.

So I'm just asking... How accurate is that? Consider someone without insurance, a minor physical ailment, a neurodivergent mind and no interest in fighting off harassing people for the rest of their life.

How much would such a person expect to pay, out of their own pocket, for things like check ups, x rays, meds, counselling and so on?