Anime ages are so confusing
This is a guy named Giorno Giovanna who goes on a life or death journey with the power to give something life with a punching spirit. He becomes part of the mafia to stop the movement of drugs in Italy. He looks relatively old.
Hah jokes on you they're 15!
_______
Then there's Jotaro Kujo. A guy who's 195 CM tall is, strong & expieriences shit that'd give anyone trauma while on a journey to kill a Vampire who stole his Great Great Grandfather's body. Looks about in his 30's
Oh whoops he's 17!
______
Now this guy. Ira Gamagoori. Probably one of the most buffest characters in existence. He is large as hell and has an extremely manly physique. "There's no way this man ain't like in his 50's" I said stupidly.
Surprise!!! He's 20!!!
_______
Now look here. This is Meliodas. This is just a kid right? Nothing odd about him. He looks normal & innocent. Now this kid I can believe is 13 or 15