Oh this thread covers so much, but back to your original topic, the problem of where did something come from, and what is nothing? I spent years of my childhood torturing myself trying to make sense of this. The answer, and peace of mind, for me came from thinking about just what "absolutely nothing" is, as that was the only thing that made sense that could be without being caused.
I don't claim this to be valid reasoning. It is just my childhood thoughts. But it makes sense to me to this day so I share it with you.
I thought that absolutely nothing had no mechanisms within it. No time. No space. No laws of physics, for the laws of physics describe describe very precise mathematical terms a set of complex behaviors, which suggested to me that some kind of mechanism was operating that causes those behaviors. No endless sea of quantum flux, or no other mechanisms that would allow a universe to big bang forth.
Then I started to think that existence was a property, and that something must be there to persist the existence of something --or the lack of something. For example, this white and brown coffee cup in front of me exists, and it continues to exist across a span of time... something seems to be persisting that state of existence. Meanwhile, the purple kangaroo in this room does not exist, and continues to not exist, so something must be persisting the lack of existence of the purple kangaroo just as something is persisting the existence of this coffee cup.
From this, I concluded that if there was absolutely nothing, the existence of something in it was undefined. I could not say that this something exists (within this realm), and I also could not say that this something does not exist.
It was easy for me to understand that something exists, such as this cup, or that something does not exist, such as the purple kangaroo. But to understand how something could not be defined to exist or not exist was more challenging. I spent a few days struggling to comprehend what that could mean before I came to a conclusion.
The conclusion that I came to was that existence was relative. If, hypothetically, it were possible to form a description of something of which, within that description, allowed for itself to exist, then, I concluded, that it exists (with respect to itself). Therefore, if, hypothetically, it were possible to describe something that provided for its existence, and provided the mechanisms that allows for the laws of physics, and for the big bang, for our universe to be created, then this universe exists within that realm.
This explanation has and continues to work for me. It provides for an infinite variation of every possible option for the universe to exist, with respect to its realm of existence. Perhaps only an infinitesimally small percentage of those are configured in a way that allows for humans to be in there, pondering things. However, as long as there is a non-zero probability, the one we are in is going to be configured as needed to allow for us to be here.