factoid
A fact that’s so obvious it’s not even worth saying. It's like a fact that just wants to be ignored.
"No shit, Sherlock.", said by a kid who just said a factoid.
"That’s not even a real fact, that’s just a factoid.", said by a teacher who’s had enough of obvious facts.
"You’re a factoid, and I’m not even mad.", said by a kid who just said a tiny fact.