First of all, molecules do move irregularly, but this movement is reflected in the micro-level, and the probability of molecules moving in all directions is the same. We can't get kinetic energy from the micro, and the macro expression of molecular motion is temperature. You can get energy from molecular motion to reduce the temperature of an object (refer to the description of heat in college physics), which is from energy to kinetic energy, and you can't let the temperature of an object drop indefinitely.
Second, gravity, I wonder if you have seriously considered this issue. In order to take advantage of gravity, you must first lift an object to a certain height. But it needs energy, and the energy consumed is equal to the kinetic energy you get with it.
Third, magnetism. I don't know how you use magnetism. The principle of magnetic force is similar to gravity. You also need to separate the magnet from the object by a certain distance, which also requires a certain amount of energy. If electromagnetic induction is considered, it is the conversion of electrical energy and mechanical energy, and external energy is also needed, but the magnetic field itself does not produce energy.
Fourth, the principle of charge force is the same as the second one.
Fifth, flexibility. . . Elastic force actually refers to elastic potential energy, and its generation also needs energy conversion.
So none of the above can be regarded as inexhaustible energy. From a macro point of view, energy will never be exhausted or generated. It can only be converted from one form to another. However, considering the utilization of human beings, the available energy is limited, and people need to save before finding new energy sources.