Reply To: If these shapes in the exercise are not deforming, why are we using an armature to animate these shapes ?

The point is to  practice using a ‘rig’ with just a few controls before you go off and use one that has 100s of controls.

And to learn the difference between animating 1 object with many controls VS many objects.

All these keyframes belong to the one animation action, and therefore can more easily be edited.