Light and gamma rays are part of the electro magnetic spectrum. Don’t be spouting silliness
You misunderstand the entire concept of Maxwell’s importance to modern civilization. Of course light and gamma rays are part of the electromagnetic spectrum - and they are also energy that could be available if we knew how to harness it - light is already partially harnessed by solar panels, but that is indirect.
Newton’s forte was a natural philosopher who laid the groundwork for the scientific revolution. Maxwell was a theoretical physicist who laid the mathematical groundwork for modern civilization - without whom Einstein would have remained a obscure mathematician working in the Patent Office and Tesla would have done something else.