Our ancestors had an "explanation" of how flint works, which enabled them to work it into useful tools, which in turn enhanced their ability to survive. They didn't need an "explanation" of where flint comes from.
If a singularity were the 1st thing ever to exist....
A singularity is not a thing. It is "where" (though it is not a place) you can no longer ask, "Where did it come from?" No logic is possible beyond that "point".
So I kind of agree with you: The universe can not be explained in the same way that a tree can be explained - but neither can you "prove" that it can not be explained. At some "point" (which is not a place) all logic goes offline; the screen goes blank.