**arrogant Mario-lore-splaining voice**
Y’all seem to be forgetting that in fact, Mario first picked up a gun all the way back in 1989, in the momotaro episode of the Amada Anime Series: Super Mario Bros.
In this Anime, Mario is born from a peach that falls from the sky and then when he grows old enough to go save peach and fight Bowser, he inherits the family’s gun.
Mario is actually born with his moustache so maybe he wasn’t born from that peach but that’s just how he got to the mushroom kingdom and the hammer boss that adopted him thought he was a baby.
(I know momotaro is a japanese folklore figure and this Mario ova is very loosely based on that story, I’m just trying to fit all of this into the lore)
The fun part about this anime is how Mario is always carrying his gun but he never shoots, not even once in the whole episode. Proving that the Brooklyn plumber wasn’t very fond of shooting guns from the beginning.
He was comfortable carrying one around and holding Bowser at gunpoint though.
Maybe something happened in Vietnam and that’s why Mario refused to shoot a gun again until 1993 in Yoshi’s Safari.