That has to be the canonical answer 
though it has to be said I loved him as a kid, so maybe the haters can suck it 
Jimmy Olsen’s only job (and Lois’ too) was to get into trouble so Superman could come to their rescue. Both did that magnificently before writers decided the characters should behave like rational adults.
Nothing else?!? What about Jimmy The Super Brain (with huge bald light bulb-shaped head)? The Wolf-Boy of Metropolis? The Human Porcupine/Octopus/Genie/Dragon/Hippie/Gorilla?
And almost as quintessential as Giant Turtle Boy is his many transformations into Elastic Lad.
As a kid, it was the first time I realized that DC writers thought their readers were stupid. Because they felt like they had to label EVERYthing… including Jimmy. His purple costume (which showed off his lack of physique) was emblazoned with, not a logo, but ordinary writing spelling out “Elastic Lad”.
Remember-tv cartoon sidekicks, not comic book.
The post-Fredric Wertham Comics Code Authority years were the nadir for comics. Look at the devolution of Lois Lane: in the Golden Era Fleischer cartoons Lane was a tough, smart cookie of an investigative reporter, who only needed rescuing when the situation was dire enough that Superman himself was needed to handle a situation the police couldn’t. By contrast, the Silver Age Lois Lane was basically Lucy Ricardo.
“Shape of… communism!”
“Form of… cat thoughts!”
Plenty of TV version of Jimmy.
All stink.