EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.
I don’t think a unique big bang has ever been the prevailing theory in science. If you ask science what happens before the big bang, the answer is “we don’t know”, and if you ask has there been other big bangs, you might get a “not that we’ve observed”, but science has not attempted to explain what happened before the big bang because in the most literal sense, we just don’t have the data to make an attempt.
Predictions do state that the future of the universe will look different from the beginning of the universe (by which I mean the universe since our big bang) and the maths suggest that before the big bang, we think there was a singularity of incredible density, but that doesn’t really deal with how many other big bangs there can have been.