What does it mean if the universe is actually built in such a way as to result in a brain which can understand it?
-SBF
. . . Then it would mean that the universe was built in such a way that a brain could understand it. Starting with that assumption - that's the only conclusion we can reach.
Perhaps a better question to ask might be, "Does a universe which can have complex systems that are capable of understanding itself (brains) suggest it was designed that way?"
My short answer is - I dunno. Even if we gained knowledge that there was a Universe Creating Intelligence - we still couldn't conclude our universe was designed. Because we have no way of telling the difference between designed universes and non-designed universes. We have no metric via which we can look at our universe and say "look - it matches a designed universe" or "what-do-you-know, it matches a non-designed universe."
We would have to know that MOST or ALL universes are created by a UCI to conclude that our universe was created by a UCI. At which point, the question of looking at intelligence inside a universe to infer if it's designed or not - becomes a moot point.
Why is reality constructed in this way to result in these apparently predictable outcomes.
Because subatomic particles behave in predictable ways. Because atoms behave in predictable ways. Because molecules behave in predictable ways. Because space/time behaves in a predictable way. Because reality behaves in predictable ways. Etc.
As far as we know the laws of physics cannot be broken. I don't think it's necessarily "constructed" that way because I don't know if a universe can exist with a different set of physics or if a universe can exist without physics all together. But I would think that a universe without physics would tear itself apart pretty quickly.
In regards to the larger questions your asking I think it's important to remember that the carbon atoms of which you and I are composed were first forged and manufactured in the heart of a dying star. We are quite literally the remnants of a stellar core. The children of a supernova. Because it's not just we who are inside the universe but it's also the universe that's inside of us. We ARE the universe . . . seeking to understand itself. And I feel the fewer assumptions we start with when asking questions about our existence the richer and more fulfilling our answers will be.