I'd recommend Max Tegmark's Our Mathematical Universe which goes into some of the more modern theories beyond The Big Bang (Inflation Theory, MWI of QM) - I thought it was pretty interesting and didn't know about.

https://en.wikipedia.org/wiki/Inflation_(cosmology)

My interpretation of the comment you replied to wasn't that they were trying to justify the argument, but just clarify what the argument specifically was (and where it came from).

What you may not see is that everything is incredibly intelligible.

Of course it is: it's a work of human writing, by people who were quite serious thinkers of their era.

But you can't use the content of the bible to prove the existence of the supernatural any more than you could use Beowufl to do the same.

Agreed, I don’t think one should try to prove the supernatural starting from the Bible.

One first has to define supernatural :)

My general thought is that at the deepest possible metaphysical level, everyone has a foundational framework that realize on untestable axioms. (Eg. we have free will)

Identifying those is an interesting exercise, but then at some point I realize that at all levels of natural depth, the universe has extreme order and intelligibility. Eg. The simulation argument is a reframing of the creation arguments.

From that point, one can surmise that some creator would be intelligible, and would likely communicate with beings that have free will. Eg. humans are a cloud of hydrocarbon atoms that contemplate their own existence.

The rest then follows, and so on

"That the universe exists" isn't a sufficient explanation since we know that it doesn't exist of necessity (since it is composed of parts). The argument doesn't say anything about what this "First mover" is like, only that it must be sufficient to explain the effects it produces (which includes being-a-person since that's qualitatively different than not-being-one). It's only when you come to the realization that to-be is the same as to-be-beautiful is the same as to-be-true that things start to look vaguely like the God of the burning bush and the problem of pain starts to raise its head (and then you have to meet the cross and either break on it or be saved by it).