Example: electric lights and firearms and radio transmissions all seemed supernatural to natives who'd never experienced them before. Why? Unfamiliarity. The very unusual is often interpreted as "supernatural" by awestruck people, but after some familiarity builds up with it, then they decide it's not supernatural after all, and they just take it for granted after awhile.

I know you already think you can divide things up into the "real" and the "unreal"....so you wouldn't for example countenance the idea of Angels being real, would you? Not for a moment. But that's for just one simple reason: You haven't seen any Angels yet. So you assume they can't possibly be real. If you did see an Angel, you'd have a very hard time maintaining that assumption.

Electric lights, firearms and radio transmissions all obey the laws of nature. Given time and decent teachers, your natives [sic] could be taught to understand the laws that make those things happen. All very commonplace, all very ordinary. A thing does not have to be familiar to be ordinary. The "supernatural" does not fall in at all here. Supernatural phenomena do not obey the laws of nature. They go against them at every turn. But here's the clincher, just to disappoint those whose flights of imagination carry them away a little too much: not one single supernatural phenomenon, angels included, in spite of millennia of claims and striving by advocates, has ever amassed anything like sufficient evidence that it exists to convince anyone except the completely gullible. I should like to suggest that there is more than enough delight, amazement and wonder in the commonplace things of this universe to satisfy the hungriest imagination. It's just that religion would like to sidetrack you into believing there's something even better. Religion is the thief of wonder and imagination. It makes you see things through an obscuring veil instead of in their bright, clear, ordinary glory. You don't see the beauty of a lily when it's gilded. You can't see the beauty of the universe through a supernatural veil.