Why Can't Energy Be Created Or Destroyed (Ik this has been asked numerous times by mine is slightly different)

Energy is not a physical substance, but a mathematical object - an integral of motion of the equations describing the world, whose existence follows from the basic symmetries of the Universe. Thus, the energy is conserved by definition.

Conservation of energy , conservation of momentum and conservation of angular momentum, are three laws developed from observation of innumerable experiments . These observations have been fitted with mathematical models that have them inherent in their formulation and thus in all solutions.

Now the question

if energy cannot be created or destroyed, how does our universe exist?

is answered by astrophysical cosmological models, that attempt to mathematically fit observations of our universe. The current dominant model is the Big Bang model, where the energy existing in our universe was created at the beginning of the universe's time once, and this is the energy we have at present. General Relativity theory, on which the model depends, allows for energy to be created and destroyed at the beginning of time and only as time advances, the law of conservation prevails.