There are, in my view, no reasonable explanations for such a profoundly amazing thing.
Just restricting myself to things I remember on FR:
1) It's turtles all the way down. 2) God whopped it up from scratch. 3) The Great fox pooped it out. 4) Baal gave it as a gift to Magog 5) It never came into being--it's always been a) it loops back on itself b) it's only one basic particle that jumps back and forth in time to weave the whole megilla c) It's part of the megaverse of universes, and our matter is interweaved indetectibly with the matter of other universes. 6) Its the illusion of a) my mind. b) god's mind c) some other mind. d) a mutually interlocked set of illusionary minds imagining each other into existence. 7) It's an attenuated adjunct of entwined superstrings in other Xverses--an afterthought, or junkyard whose laws and motions are created to provide counterbalance, damping, and waste dump to more rationally operating universes. 8) It's the equivalent of a miscellaneous particle in a super-universe, which is, itself, a miscellaneous particle in a super-super-universe. 9) 8) with a loop. The highest universe is a particle in our universe.