The Grand Universe Theory
A world has its own mechanisms and selectively-permeable membranes between it and other worlds. The grand universe is an organism made of all cellular worlds.
One world has its own set of fundamental physical laws, which support the information ('life') within. If information passing through the barrier between worlds is not supported by the recipient, then the information will be converted into a form that it can support. Thus, magic-fueled creatures become non-magical animals or computer programs; their information is preserved, but is stored in a different format.
The grand universe theory: an acknowledgement of the existence of each of these worlds as parts of a whole system, exchanging information in metaphysical metabolic processes.