It can be produced in a renewable manner even if it currently usually isn’t (though it is a net consumer of energy to create it that way, so it’s more like a sort of battery when used that way than an energy source), so if the downsides can be worked around and the economics worked out (a difficult proposition I expect given hydrogen is in a similar position and all the issues that one has) it has potential to work as a renewable vehicle fuel.
The last bit about the big bang isn’t really how it works to my understanding. The big bang is compared to an explosion, but its actually more like a balloon inflating, if you imagine the surface of the balloon as analogous to space. The galaxies don’t all move away from some original center to the universe, new bits of space get “added” in between every bit of space, so that every object gets farther away from every other object. If you go backwards in time far enough, every point sees itself as being the center. At least, that’s how I’ve seen it explained.