People
Lord Emsworth had an IQ of an average jellyfish.
— P.G. Wodehouse
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker delivers a comic insult, describing a character's intelligence as being no greater than that of an ordinary jellyfish. It's an absurd, deliberately deflating comparison meant to poke fun at obliviousness or slow-wittedness through a whimsical, mildly ridiculous image.
Context reviewed