Mathematician here, so educated layman on the physics but expert on infinity if you like.

Mathematically, "infinity" doesn't imply every possible option. But in terms of quantum physics, yes it kind of does include every possible option. There is a kind of joke classroom exercise in quantum physics class to calculate the probability that a piano would instantaneously rematerialize a meter away from its previously observed location. Its 10^-[ ridiculous number] but still thats not zero.

The size of physical reconfiguration of a person's brain to cause them to break out singing is a much smaller deviation so comparatively likely. So 10^-[somewhat less ridiculous nunber]

The bigger issue with all those non-zero probabilities is they're meaningless while you still experience actual time as a human...but become pretty damn significant when you experience no time after you die.

So tiny probabilities become essentially guarantees unless the heat death of the universe is so thorough as to erase the slight probability that the whole thing pops back into existence.