It could also be an interpretation thing. We often forget how riddled with context our natural language is.

But what about things that do not understand this context? For them, the request to "jump high" is not as easy. What distance is high? You could argue that athletes jump high, but in the eyes of the athlete they jump normal and they are expected to jump that high regularly, so that can't fit the bill for the wishgranter.

What about jumping to the stratosphere? We already get gimped by context, because you can't get a good context because jumping up there dwarfs in comparison to the humanly inconcievable distances such as jumping from one end of the universe to the opposite end. So using a distance is also a bust.

The last resort is reference. Frogs can be defined as "an animal that jumps high", so turning you into a frog is the safest bet to fulfill the wish without violating it through ambiguity, because you can't deny that you can see frogs as an animal that jumps high.