Cool! I'll be doing something similar with my "Steemit Art School" idea. If I can work around this big new project I was hired to do.

I think you did a good job explaining negative shapes! The only thing I would add is that these shapes are not just things to become aware of, but learning how to consciously manipulate and design them to clarify your picture.

On my dragon picture, notice how I used the negative space to make the silhouette read clearly. Every part was a decision.
https://steemit.com/dragoncontest/@gabrielvalles/my-dragon-for-dragoncontest

Hope this helps!