Our inability to understand and accept physical truths is irrelevant to the universe - it doesn't care what we believe ... so arguing that existence can only be explained by the supernatural is just publicly displaying our lack of knowledge. It is an argument from ignorance.
How do we define "truth" - so that we can discuss the difference between natural and supernatural explanations for phenomena? Without getting into various theories of truth - a good operational definition is that truth is the model that best explains the material patterns that can be examined and confirmed in the physical world.
When we say "gravity is true" or "gravity is real", we assert that a ball will fall to the ground when we release it - every time - throughout all eternity, as long as no counteracting force is applied. Yet we still refer to gravity as a "theory" - first with Newton's theory, then with Einstein's theory of general relativity that ascribes gravity to spacetime curvature.
When you believe in the supernatural, you do so without evidence and rational justification. Attributing existence to a "creator" - an entity onto which you then project the characteristics of eternalness, omnipresence, omniscience, and the ability to interact with you and provide benefits for you and those you care for - or occasionally, disadvantages & retribution for those who you disfavor - this requires abandoning reason and your own senses. Oh ... and did I mention the afterlife? The addition of an afterlife sure makes it more believable.
Where, in this universe, is there credible evidence of anything supernatural? Why would extending this wholly unsupported, irrational conception to a hypothetical ultimate being (god) make sense if the simplest evidence of lesser supernatural conceptions has never been produced - let alone verified? Why, if there is no such thing as ghosts or angels or demons, is the idea of a god worth broaching in social discourse, let alone subjecting to the scrutiny of rational inquiry?