I will give a rather unconventional answer. Energy is the 'state' of an object in space and time, which can be defined as a combination of two things: the mass of an object, which is the intrinsic unchanging component of 'state', and its motion in space and time, which is the extrinsic variable component of 'state'. So mass is generally considered to be constant for an object, and motion is variable and represented as distance and time. Motion can be in the form of translational motion(one place to another), vibrational motion or rotational motion. Both mass and motion are needed to accurately describe the total 'state' of an object i.e. its energy, which can be in different forms. For example, at the atomic level, the 3 forms of motion, combined with mass translates into heat energy.
That was the qualitative definition, now for the quantitative definition. The question is how would you mathematically combine the definitions of mass and motion to give an appropriate mathematical definition for energy? The answer is not so straightforward, and this is where the equations come in. So then we come to 2 basic ways to describe useful notions for energy:
$$K.E. = (1/2)mv^2$$
$$E = mc^2$$
The first equation represents dynamic state that depends on motion, and the second equation represents the base invariable state that is independent of motion. They both seem to represent useful values, which are conserved. You may be wondering where the equation for work done is. The equation for work done represents the change in kinetic energy, and are two different aspects of the same thing. In fact one can be derived from the other using $F=ma$ and kinematics, as shown here:Where did the kinetic energy formula come from?
The equation for kinetic energy is better suited for scenarios in which an object is moving at a constant velocity, with no net force acting on it. The equation for work done is better suited when there is a force acting on an object. Potential energy can simply be seen as the potential motion an object can make, arising from multiple forces acting on that object that vary with time.