The multiverse need not have different physical laws; the quantum multiverse if true, for example, is basically our universe just viewed from a different point of view.

"Humans can not directly observe an alternative permutation, but even if they could, how would they be able to find their way back to their original permutation if there's an infinite number of permutations?"

Unsurprisingly, science fiction authors have pondered this for a while, and one popular answer is a travel machine where part of it still stays in the universe of origin, so returning home is like pulling a rope back in. Even if we're in a quantum multiverse where the source universe and the destination universe are continuing to fuzz, you can still imagine there's some sort of correspondance that means that any given individual will still have a uniquely-corresponded universe to travel home to.

I believe this is all technobabble bunk since I doubt it can correspond to any possible real configuration of atoms and energy, but, like I said, someone could well prove me wrong by building one, and that would be that.