That most people are much dumber than they initially appear to be. “Average intelligence” isn’t enough to form a basic understanding of the world.
But you aren’t one of the dumb people right?
Not OP but I can fully accept I’m a roving idiot ¯\(ツ)

One time I tried pump my fuel and it kept stopping right away. I moved pumps and the same thing. I was looking down the hole to see if anything was blocking it, I went inside to inform the attendant their pumps might be malfunctioning. Then I realized, the night prior I had already filled up. I’m a dumbass.

To my credit, however; it is my routine to fill up every morning (I drive courier) A night fill up was off routine. Still a dumbass.

I thought the ac was broken in my work truck for several days in July because I forgot I had turned the heat on one chilly morning and for some reason my eyes repeatedly didn’t catch that dumb temperature dial still turned to heat. I kept pushing the ac button on and off and then just ended up sweltering because I basically had the heat on in July.

That dumbassery will humble me for a while.

Another victim of the routine autopilot. It gets us all from time to time.