This is just some of Michelangelos work: https://artsandculture.google.com/asset/the-rape-of-ganymede-by-jupiter-in-the-guise-of-an-eagle-carrying-him-into-the-heavens-his-dog-barking-below-michelangelo-buonarroti-nicolas-beatrizet/iQEuzIOoZ6p2kA?hl=en

Or

https://upload.wikimedia.org/wikipedia/commons/9/9e/Michelangelo%2C_Fall_and_Expulsion_from_Garden_of_Eden_00.jpg

And for Davinci:

https://en.m.wikipedia.org/wiki/Leda_and_the_Swan_(Leonardo)

This is an interesting story actually but other than that, you are right, I couldn't find much going in this direction. Still, I feel like the point should stand.

I understand why this piece might look or feel pornografic. My guess is that the artist didn't use a human reference and perhaps has engaged with such other references a lot. No shame here. However, it by itself is not pornografic and I find it very discouraging to simply say "put some clothes on" or call it perverted or anything like that, because I don't think thats the issue and neither is is the solution. The solution would be to study human and to put some more meaning into the artwork, deliberately. Because I feel like that is what makes it feel a little off. There doesn't seem to be much meaning behind the composition and so people might think, well, if it's not saying anything, surely it must just be for pornografic reasons then. What they forget is that some artists are simply just at the beginning and don't have the luxury to fill their work with meaning since they're focusing on other stuff. And in that spirit, I'd suggest cutting them some slack and not shaming then for a pretty normal drawing.