Universe from Nothing?

[Esquilax]

I say, "It's a loaf of bread - these things don't arise by themselves
anywhere else in human experience.
All the loaves of bread that we can actually see and measure
don't do what you are suggesting."

This, right here. This is the part where your comparison to the universe breaks down.

You're right: loaves of bread have never arisen by themselves anywhere in human experience, and all the loaves of bread we have to compare to have been baked by human intervention. You're dead on correct, and we can see, measure and confirm this.

But what other universes have you been able to investigate? Where's this large succession of alternate realities that you've compared this one to, and more importantly, even if you had them, how would you be able to confirm that they were designed in order to make that comparison in the first place? Do you have a designer out there making universes in front of you, so you can confirm that?

Your analogy presents us with an object that we can compare and contrast with the natural world and other examples of it and thus of course we can determine its nature as a designed object. But you have no other universes to enact this same process on the other end of the comparison, and comparing the universe to things within it would be fallacious in the extreme. In a very real sense, it'd be comparing apples and oranges.