How do we determine what is supernatural if the universe is so big that it allows nearly anything to happen, thus everything is natural?

Yes; supernatural is a term that describes a degree of normal. Just like how "hot" describes a degree of warmness. Even magic, if it were real, would be natural. You know what?; I didn't realize just that it works this way, until someone pointed it out on "Yoohoo Answers". There are probably a countless amount of things that one could learn from that site alone. I juts hope that each thing I read there, I can document it here and offer some insight into everything that there is.