That's not quite right ─ molecules hang together in many particular situations ─ but I see what you mean. One difference is that our understanding of molecules is derived from our sensory perception of our education, rather than directly of the molecules themselves.Yet the shapes we are speaking of are not as subjective as a park. We are talking about definitive structures that exist. While you can widen or narrow the frame of reference, we are discussing distinct objects, where those distinctions hold relevance.
No matter how much you widen or narrow the frame a molecule remains distinct from those surrounding it. That molecule has a definitive structure that is a shape.
But I'm not sure that I've understood the point you're making. Not only can we widen or narrow the sensory field of relevance depending on our intention / purpose, but no matter what our sensory input is, we gather its meaning relevant to us by interpretation ─ or we pay it no attention, just edit it out, like the other conversations in the room when we're at a party, or the seats in front of us when we're watching a movie. Even when we sleep, we can respond to particular sensory cues, waking up or occasionally incorporating them into dreams.