Energy is just motion. Gravity is a potential. If a mass is accelerated by the potential, then that acceleration, that motion, is the energy caused by the gravity potential.
Mass is the motion of matter. Matter motion. Energy is ANY motion. We can add energy, motion, to matter. We can retrieve motion, energy, from matter.
Energy is any motion. Mass is matter motion. That’s why energy and mass can be ratio-ed.
The matter motion is called inertia. It’s an acceleration, a constant acceleration. It’s this acceleration, this internal acceleration, that opposes external acceleration. Inertia.
Inertia is NOT gravity. But both gravity and inertia are angular. And angular interaction is much different than linear interaction. Attraction, repulsion and balance are different. Because both are in states of acceleration, not just velocity.
Just a passing comment.