Energy in physics feels analogous to money in economics. Is a manmade medium of exchange used for convenience. It is the exchange medium between measureable physical states/things.
Is energy is real in the same way money is? An incredibly useful accounting trick that is used so frequently it feels fundamental, but really it’s just a mathmatical convenience?
Small aside: From this perspective ‘conservatipn of energy’ is a redundant statement. Of course energy must be conserved or else the equations are wrong. The definition of energy is it’s conservation.
many have answered that as a concept, it is made up. But it is arguably the most real (and important) thing in all of physics (or maybe action, which is also some function dependent on energy). the money comparison is fine, if we have different forms of denominations of money (currency notes (different amounts), gold coins, etc) we have different forms of energy quantas.
Here is a viewpoint to understand - almost everything acts in a way to minimise total system energy. this can be (almost) made valid all the time if you include some probablistic factors. (If we take thermodynamics (which is by definition study of dynamics of energy(and heat, which can be considered as some kind of raw energy), then we include entropy, which is basically finding how many ways can a particular energy can achieved.). This is not a very rigorous way to put it all, but basically all of physics basically works on energy. Forces are basically caused by some kind of gradient in energy.