Ah, Grasshopper, there are many things beyond your understanding. The fabric of the universe, which is what expanded at the time of the Big Bang, is not matter, or even energy, and is not mathematically restricted by those limitations. It is merely a boundary.
Of course, that is merely one theory of the origin of the universe we inhabit. Is it the correct one? I do not know, young Master Pikachu. Perhaps the creating entity waved its appendages and this Big Bang occurred. I do not know that, either. Perhaps it is merely the science experiment of some youthful non-universal entity in some other plane. I do not know that, either. I do know that we appear to be part of a universe with some essential physical laws. How that universe came into being is not knowable by this lowly human. As to the origins of life on this minute speck circling a rather insignificant star, I cannot speak, either. Those origins, at the moment are a matter of hypothesis.
And perhaps His appendages were Noodly!