i mean, i don't know how it is in other countries, but here we literally study art with nude people in it - Liberty Leading the People is part of the 8th grade national curriculum - and looking this up, i even found a teacher's blog about class activities they did on it with 3-5th graders. i also recall having studied paintings depicting people having sex in 8th grade latin class
it's also not uncommon to have statues of naked people in the middle of town centres - and nobody is making a fuss about it "not being art"

it is art, it used to be recognised as art for a long time, but now it seems like more and more people have a double standard, where old art depicting nudity is valid, but modern art depicting nudity isn't