I’m glad we agree that the “unknown (potential) natural” does not equal the supernatural. Otherwise, I think we both agree that would be a textbook example of arguments from incredulity or “supernaturality of the gaps” type reasoning.
Relative to how you do define the supernatural, I guess I don’t quite follow how something necessary to explain existence and operation of nature is supernatural. For example, if it could be shown to your satisfaction that the cosmos has always existed as the necessary grounding for all that we observe…would you call that supernatural?
The cosmological argument doesn’t demonstrate a God exists even if you accept all the premises. It simply demonstrates that our present local universe has a cause. I do not accept the cosmological argument (nor do the majority of cosmologists) because the Big Bang isn’t a demonstration of the “beginning” of our universe, simply the expansion from an initial low-entropy state. We do not observe our universe “beginning to exist” so I reject that premise. Nor do we actually observe (in a sense) anything beginning to exist. We do however, observe a perpetual rearranging of energy and matter into different states that we label as beginning to exists. For example, in a sense we don’t observe a chair “beginning to exist” we do however observe a rearranging of matter via energy (humans constructing things) forming various amalgamations of matter into a different constructs and eventually that rearranged matter will rearrange into different matter (ie tree is turned into a chair, which goes to the dump, which then is decomposed into detritus, which then is absorbed by various forms of bacteria, etc.). There is no reason NOT to assume that this perpetual rearranging of positive and negative energy has not always been the case when you explore zero energy theory. All other arguments that proport a God to exist are arguments from ignorance (ex. you cant prove me wrong therefore I am justified in believing in God) OR they are arguments from incredulity (ex. I can’t think of another explanation therefore I am justified in believing in God).
I do not accept the supernatural as metaphysically necessary because we have no way of differentiating the supernatural from the natural, therefore we cannot appeal to the supernatural as explanatory (we would be appealing to a mystery using a bigger mystery that seems simple, but is in reality far more complex than any natural explanation).