i think the painting was antisemitic. it looks a bit like the caricatures of Jews in Der Sturmer, and the cartoons of nazis by George Grosz. Thus accusing jews of being fascists and the orchestrators of all the world's economic problems simultaneously.

however a lot of people can't see it.

i think the likeliest thing is that Corbyn didn't pick up on the cultural references. After all he didn't know the Punic Wars were with Carthage, so he's not the most clued up guy in the world.

However, he's a lot nicer than any of the alternatives.