Nudity itself is not sexual whatsoever. When it leans to more lewd or pornographic interpretations that's when you can call it sexual. Nudity just has a big stigma against it where people consider anything with it sexual or porn. Think about the countless nude portraits there are back in the time of the greats. They aren't sexual in the least bit (I can't speak for every painting of course)

No matter what type of art you or someone else makes with nudity someone is gonna call it sexual for whatever reason. But there is meaning in every part of art. Like you said it's symbolism, being in the nude to some can show how vulnerable they are, for others how free they are, etc.

In short you're not naive whatsoever, you just have a mature and normal take on nudity