> In fact, if something created existence, that would require an entity that operates outside of our current understanding of physics.
Obviously. I suspect you don't know that much about physics, but that's kind of implied: You can't create the laws of physics from within the laws of physics.
> What evidence do we have for this theory?
Conservation of energy, entropy. It's very well accepted that whatever created our current laws came from outside the laws.
There are some scientific explanations for the existence of matter, but none for the existence of the laws. The closest anyone comes is the idea that all possible laws exist (multiverse) - but of course that doesn't answer the question of where the framework the existence of any laws at all comes.
> Maybe there are more laws of physics to be discovered.
Maybe, but that doesn't answer the question of where those laws came from. All you did is move up a step, but you answered nothing.
> there were numerous supernatural explanations
Not really. The explanations were actually scientific - look up Aristotelian physics. They may have been wrong, but they were entirely secular.
> Does a god pull the sun across the sky in his chariot each day? No!
No one actually believed that. It was part of legends and stories told for entertainment.
> posits that the limitations of our current scientific knowledge must be explained by the supernatural
There is only one limitation that needs the supernatural: The existence of nature. Lets say our world is a simulation on a computer. Does that count as a natural or supernatural explanation to you?