Handedness really just kind of depends on the activity you're doing.
I write with my right hand so I'm "right-handed." I feel like we just go with that.
Meanwhile, I play hockey left-handed, and I batted left-handed in baseball even though I throw right-handed. People say "oh, well, the baseball thing is normal and shooting LH in hockey means you're actually right-handed."
Ok, but here's the thing: I also golf left-handed. There are fewer left-handed golfers than left-handed people by percentage. Why is that? Is it not the same motion as hockey? I don't know, that's weird.
You wanna hear something even weirder? I speed-solve Rubik's cubes competitively (I know, what a nerd, but that's not the weird part); the weird part is I'm violently right-handed when solving with two hands (yes, two hands, stay with me). I will make extra moves to put the layer I'm working on in my right hand. It's terribly inefficient and it's one of the weakest parts of my game.
When I do one-handed solves (yes, that's a thing), I do them exclusively in my left hand. I can't one-hand solve a cube in my right hand. Can't do it. It's like a turtle trying to drive a car.
And who's to say holding a hockey stick left on the bottom and right on top is "left-handed" anyway? Why isn't that the other way around? It feels arbitrary.
TL;DR: it's all bullshit and we just base everything on what hand you hold a pencil with.