Like you say, we have no way of knowing if there are other "Universes" or whether the Universe as we know it was part of another until the Big Bang happened.

If as I speculate, if there is another Universe (or more), the enormous Black Hole that eventually exploded due to the heat and pressure could have formed "there".

Also, we don't know where our Universe is expanding to? For all we know, the expansion is due to it all heading for someplace else where, over trillions of years, the whole thing will take off all over again.

Again, we've no way of knowing how many times it's happened. Our time is short in comparison to the age of the Universe and it's only a relatively short time since the scientific world stopped explaining the inexplicable by tales of mysticism enacted by all-powerful beings.......