There are alternative hypotheses like Eternal Inflation, and Blackhole Cosmology. Mathematical Universe hypothesis would have our existence merely be one expression of consistent mathematical laws, all possible variations of which exist in a level 4 multiverse. Or we could just be a Boltzmann Brain that only imagines it is a universe that started with a big bang and real physics are markedly different.
It is worth keeping in mind that reality is under no obligation to make any kind of sense to us.
It is worth keeping in mind that reality is under no obligation to make any kind of sense to us.