In any finite region of space, matter can only arrange itself in a finite number of configurations, just as a deck of cards can be arranged in only finitely many different orders. If you shuffle the deck infinitely many times, the card orderings must necessarily repeat.

How can a speck of a universe be physically identical to the great expanse we view in the heavens above?

We do not know whether there are extra dimensions or multiverse. Let's go forward with the possible ideas that come out of the mathematics. It's hard for us to imagine a universe that would have no time at all.

...things are the way they are in our universe because if they weren't, we wouldn't be here to notice.

Relativity challenges your basic intuitions that you've built up from everyday experience. It says your experience of time is not what you think it is, that time is malleable. Your experience of space is not what you think it is; it can stretch and shrink.

Exploring the unknown requires tolerating uncertainty.

You should never be surprised by or feel the need to explain why any physical system is in a high entropy state.