I don't think I've read the 'God of the Gaps' argument so many times in one thread, along with someone using the word 'god' describing it exactly as common parlance and the religious community use it, but denying it means that...
I also love how the OP is questioning one scientific theory descrbed by physicists, by using something else described by the SAME physicists, who apparently haven't noticed that these thigns contradict eachother, and posts it on a computer forum instead of going and doing some research. As posted above, I recommend PBS SpaceTime on Youtube for all things physics related in a comic format by people with actual PHD's in this subject who know what they're talking about.
Summary - the Universe is expanding (fact) and current estimates but the age of it at around 14 billiob years based on numerous sources of evidence. Given the confidence of this evidence, the exact age will likely be narrowed down further (especially with the James Webb telescope) but will not be suddenly found to be billions of years out. Simply put, the entire standard model of physics would have to be rewritten, and it works too well for it to be THAT wrong. We can go back to about 10^-43 seconds after the initial moment of expansion (the Plank time) but beyond there our understanding breaks down, as the conditions simply didn't allow our laws of physcis to exist, and so beyond that the answer to everything is simply "we don't know". Any claim to knowlege at this point or earlier is simply being dishonest.
The funniest part about people calling the Big Bang an explosion is that it wasn't even meant to be a serious term - the astronomenr Fred Hoyle favoured the steady state hypothesis of the universe always existing and attempted to make fun of the expansion hypothesis by calling it a 'big bang', a name which then stuck as it was proven to be accurate. The idea that there was 'nothing', and then it exploded, makes me chuckle but completely misses the entire concept. It weas simply expansion from an incredibly dense point, more than that we do not know.
Personally I like the idea of the Multiverse, where infinite universes spontaneously come into existance with random settings for the various constants that exist in ours, and most of them instantly failing due to not being stable. Some, like ours, have combinations that work and so ours exists in the condition we observe today. Absoluytely no way to prove any of it, and I doubt there ever will be, but it's a neat solution which appeals to me as a lay-person. No idea where the multiverse came from either...
I'll leave one of my favourite videos from Veritasium here, showing how we used a supernova who's light followed different and predicatable paths to prove so many of our ideas right.
