I can see you have put a good deal of thought into this question, and it is certainly worth consideration. Talk of other universes doesn’t add much to the discussion, because the same questions exist…how were they formed? by a force? or just by happenstance. This topic ultimately hangs on a single question: do all occurrences have causation? If they do, you would have to admit a very powerful entity created the universe( the one we live in). What you would call this entity doesn’t matter, because it doesn’t care what you do or what your thoughts are. If the universe always existed, that obviates all mathematical models pointing to a big bang occurrence, subsequent cooling of gases and formations of planets,etc. It means that carbon or other dating systems are incorrect. It indicates our measurement of time is faulty. If you say, it just happened, then I would ask you to think deeply upon the different forces, elements, particles and myriad other things that must happen in order for the universe and man to exist at all.
Actually, talk of other universes can add a great deal to the discussion. If the death of one universe leads to the creation of another, you have a mechanism for an infinite chain of universes.
Do all occurrences have a cause? Assuming that even quantum effects that appear to be random have a cause that we just haven’t identified, then yes, they do. If every universe is caused by the end of the universe that came before it, then we have an infinite chain of universes, each with a physical, non-supernatural cause. Yes, it’s basically impossible to comprehend an infinite chain like this, but it seems to me that logic requires something to be infinite. Why couldn’t that infinite thing be a deity? It could, but that, in my opinion, is just adding to the equation unnecessarily.
I don’t “have to admit that a very powerful entity created the universe” because I see no compelling reason to think that any entity created our universe. An infinite chain of universes also works quite nicely with the Big Bang, etc. This doesn’t contradict our current view of scientific reality at all.