Y is it embarrassing to be seen naked by the opposite gender rather than same gender? What's the difference if we're all humans? And y is having those private areas seen any different than having like your feet or legs and stuff seen? Yah I'm embarrassed to be seen naked but I don't know the real reason.

Well, it is embarrassing just less so because your gender has those parts and in general, they aren't attracted to them. Don't say I'm anti-gay cuz I'm not but that was and still is the general belief that girls won't be attracted to girls and boys won't be attracted to boys. Also, a lot of places they aren't as conservative as us but we are conservative about that because they are attractive and promotes the wrong emotions. Don't hate on me for this answer because it's the unfortunate/ See More fortunate truth.

Well, cos they're male (if you're a girl, or female if you're a boy) it makes you feel vulnerable being naked. You've got no cover (literally). When people stare at you, it's awkward and one of the reasons being naked is embarrassing is because people stare. They can't help it. Unless they close their eyes. But yeah. You generally don't show your body to the opposite gender unless you're going to the doctor's, or unless you're going to have sex. Which makes people uncomfortable.

I think it is about how we were raised. A couple hundred years ago it was scandalous to show your legs and now it's normal. So if everyone were nudist then we would find that normal because that is what you grew up doing.