Let’s talk late ’90s, maybe scrape the 2000s, this is what I thought at various points in time:
1) People live forever (NB: major blow when I found out that wasn’t true).
2) There are around 130 people on the planet.
3) 120 is the biggest conceivable number (due to it being the maximum value on the tape measurer).
4) Anyone I don’t know (i.e. strangers) automatically know other strangers.
5) Animals can talk to each other, but it is a mystery how snails do it…
6) Liking a girl is gay.
7) Trees can think.
8) CCTV cameras can read our minds.
9) Women only wore dresses.
There’s probably a lot more of this trivia, I’ll put it in if I can remember any more and can be bothered to add them in…