"it's the simplest answer that makes the most logical sense!" Or, at least, the one that makes the most sense to God is the simplest, to God.
I like your way of looking at this. I use "subset within a set", yet somehow the notion that the real, i.e. God's economy, can be called a set, just doesn't 'set' right with me. Maybe your "sphere" is better. I know that the reality of himself is the default fact, and everything else is outside that, in some way. Yet it all came from him, so... In the end, I have to conclude, at least, that Simplicity is the beginning. The complications come with our need to arrange thought, I think. Consider the notion, for example that God needn't consider whether something he is going to do is good or not; he is good, and he just does it. The definition of the term, "brute fact", feels good to us; it refers to something solid that doesn't move around on us, but just simply 'is'. But in the strictest sense, God is the only "brute fact". He is the only necessary truth.
One of my favorite quotes I posted below in an answer to JAL,
#1,927 deals with this, our inability to approach full knowledge of God during this temporal dependence. We are simply ignorant, presumptuous, like children full of noise and emotion in an adult world, thinking life is about us. Worse, actually.
Here's a quote from CS Lewis' "Till We Have Faces - (A Fable Retold)" that I hope you can take without too much indigestion (Lewis is not saying there are gods (plural).)
“I saw well why the gods do not speak to us openly, nor let us answer... Why should they hear the babble that we think we mean? How can they meet us face to face till we have faces?”