" Can we agree that outside of the human imagination, at the very least, existence and physicality are one and the same? "

This is tricky. Most people believe there's a clear line between "outside" and "inside" their imagination, but the fact is that the line is far from clear, if it exists at all. "Reality", "physical", "existence", "imagination", those things are just generalizations of human experience. In truth, all we have and all we will ever have is experience. Experiences can only be meaningful in the context of other experiences, but taken as a whole even "experience" itself becomes just another generalization, for something which ultimately cannot be spoken of.

Which is why most people do, and always will, believe in God.

Cheers,

Aurino