If God didn’t create the universe, then what did?

Multiverse

Some people believe in the multiverse. A construct that gives birth to countless universes. Since there is suppose to be so many universes, this means that eventually a universe will arise that is fine tuned for life. It is inevitable. However, where did such a construct come from? And what is math that describes physical reality, but a language that is perfect. But how did math come to be but not for a mind.