that the more detailed a prediction becomes, the less likely it is to be true

That looks like part of the definition of probability.

Bayes would be more like 'If you've got two ideas about what's going on, and one of them says one thing's going to happen, and the other says a different thing, but in the event it's the first thing that happens, then you should believe the first idea more and the second idea less'.

Or to get a bit less abstract, say you're playing dungeons and dragons, and and orc hits you with a sword, and you're pretty sure that orcs do either 1D12 or 2D6 of damage, then if the orc does 2 damage, you should think 'probably 1D12', but if she does 7 damage, you should think 'probably 2D6'.

Does anyone know of any games that normal human beings play that could be used in this sort of example? I mean, apart from, you know, life.