Intelligence is the ability to make models. General intelligence means that a sufficiently large computational substrate can be fitted to an arbitrary computable function, within the limits of that substrate. Humans might already be in that category, for a rather small substrate.
The general form of a mental representation is a probabilistic algorithm, computing a function that realizes a model or controls a behavior. Learning is compositional function approximation. You want to be able to use any function that runs efficiently on the available substrate.