What is energy?
Energy is a concept that can be applied to a variety of situations. It is not the same thing in any of them. Clearly the chemical content of gunpowder and the movement of a bullet are not the same in any respect, but there is a numerical quantity that is conserved as something is conceptually transferred from one to the other. But energy is not like a magic juice that flows from one place to another. It is a mathematical computation based on the specific situation. Back in Newtons day, it wasnt a thing, but it has proven to be an exceptionally useful concept.