Like, you can see a leaf on and think “wow, that’s a beautiful leaf”. You may even pick it up to admire it (especially if you’re a child or a biologist). You wouldn’t do that with a strand of human hair, a human nail clipping, or even less with the parts that aren’t supposed to come off like hands or eyes.
You might draw, paint, or sculpt a hand or an eye in isolation specifically to explore its beauty as a discrete object without making the viewer think, “jesus christ, someone died.”
Photography is often used to isolate pieces of humans for viewing and enjoyment purposes.
Good point. Tho they’re usually implied to be part of a whole that we can’t see, as if seen through a window. They take poses that only make sense if attached to muscles in the arm…