Umm, no. My own answer is the correct answer: I don't know. Most people simply can't handle that truth and prefer to make up fairy tales.
But regardless, no matter what answer one finds satisfactory for the origin of the Trinity then from a rational standpoint that same answer will always be equally satisfactory for the origin of the universe, which is why the false dilemma that was set up by OK is a meaningless argument, and a fallacy.
Um yes. Catholicism is faith based. When you state " Whatever answer works for the Trinity works just as well for the universe." I take that at it's face value. The answer that works for the Trinity is faith. Feel free to edit your statement.
As for fairy tales, I have no opinion or interest in what you do or do not consider to be fairy tales.