I would have to see the full project but my guess would be that you swapped the parameters but not the values, and as they're both Vector2 (I think) you didn't get an error.
The jump requires the direction vector components to be -1.0, 0.0, or 1.0. And with a speed vector that's much longer, you would fall out of the code's expectations, making jump not work.
But that's just a guess.
When you define a function's parameters, for example:
func move(speed, direction):
The parameters are just identifiers for the first value and the second value passed to the function. For example, if I call the function like so:
In the move function, speed will be equal to "hello", and direction will be an empty array.
The name of the variables you pass to the function do not matter, you're passing the values behind these variables. So if you invert two variable names, you're inverting the two corresponding values in the function call, breaking it.