When did the sense of modesty around nudity first appear?

Salaam alaikum, I know it might sound a bit random, but I've been thinking about this. From what I understand, haya came about after the story of Adam and Hawa, right? But then I wonder about old cultures, like some Native Americans who used to go around without covering their upper bodies. Why was that normal for them? And now we see people dressing more and more revealingly-is that like they've just lost that sense of shame, similar to what happened back then? JazakAllah khair