I don't know how the Universe began. And I think it's an honest answer. It's better to be honest than to make things up, in m opinion.
As I understand Sean Carroll, our universe is just a small part of all there is.
Here is a list to a short video on youtube about this.
These are good questions to which I don't have the answers to. So, I don't know.
I think of these questions as trying to explain how Earth can be an oblong spheroid 300-400 years ago. You would have to know way to much and the explanation would require lots of scientific knowledge that was not commonly available and not easy to explain.
I'm not saying that I have that knowledge, only to coney the difficulty raised by such questions. I think the reason we don't usually question an oblong spheroid earth is because we see photos and images that help us understand the days/nights/seasons.
Flat Earthers have their opinions too, but they are the fringe group, which also shows the difficulty scientists face. No matter how well your explanation can explain the reality, not everyone will be convinced by it.
Perhaps you are right. Same thing can be said about God too. If he always existed, as Christians believe, then he can produce intelligence and there would be no limit to intelligence.....
This is a tough question. For sure, my birth was a natural one (i.e. I did not grow in a tube in some science lab, as far as I know) and yet, based on human biology we know that men produce far more sperm and women eggs that ultimately end up fertilized. What are the chances that that specific sperm inseminate an egg which created me would create me?
I think the scenario is virtually improbable, and yet, here I am, and here you are.
I think these 'what are the odds' questions are blown out of proportion by the religious. Think about it. I can go and have sex with a woman and produce a child. The odds of that child being born out of one of my sperm (out of millions sperm) would be highly improbable, and yet, we know unprotected sex frequently results in pregnancies leading to birth of children.
That pregnancy, which would be virtually guaranteed due to having unprotected sex can be made to look like a miracle if we start asking...what are the odds of this or that.
Further, I was born in the USSR. I'm now an American. What are the odds of that? What are the odds of my grandparents surviving WWII and giving birth to my parents? What are the odds of the particular couple coming together and having children vs other people they could have had sex with? The list goes on and on, and you can make any natural phenomenon into an incredibly unlikely miracle.
Ok, but God is infinite and that doesn't stop him from doing this thing, no?