why does steven act like a baby

i'm rewatching the series and really love it (i thought it was kind of corny and annoying as a teenager so i dropped it during s2).

one thing i'm not a fan of though is ... why is steven sooo infantile 😭 if he was supposed to be an 8yo it'd be a bit more sensible but he's 14. it's not like he's sheltered. maybe i missed something is that ever explained? or is it just cartoon logic Silly Dumb Protag stuff