Nintendo has been making some changes with Mario over the years. Back in the day, he was a plumber who hopped in and out of pipes on quests. Then the official page for Mario on the Nintendo Japanese site suggested he was no longer a plumber.
Mario's profile has been updated again and he is now back to being a plumber. The last Mario game was Super Mario Odyssey that saw Mario chase Bowser all around the world. In that game, Bowser did call Mario "plumber boy" at one point.
That was a clear indication of Mario's roots even if he wasn't running through pipes. I always thought of Mario as more of a carpenter after Donkey Kong in the arcade. When I saw him as a plumber in the Nintendo games later it was a bit weird to younger me.
At least now Mario is officially back to plumbing. Back in September of last year, his official bio indicated that he was an athlete of some sort.