(The nude-but-not-sexual viewpoint is pretty valid, but some of the fine art is definitely sexual once you know the context, and some of it was controversial in its time e.g. https://en.wikipedia.org/wiki/Le_D%C3%A9jeuner_sur_l%27herbe )
This is true only for very unusual definitions of “always” and/or “fine art”; history is more than Victorian England.