I see your json main brackets are [] which means it's an array and not an object.
It's a special case which requires you to mark the "IsArray" checkbox and choose the "Main Array Index".
In the example below you can see I asked for the second index.
The "Path Preview" is '/' because you ask for values at the first level and they have no key.
The "Main Array Index" tells us which member to take when there is no key given on the first level.
Your json: [ 1 , 2 , 3 , 4 ,5 , ..., 23]
What you tried to do is for a json that looks like this:
{
"level1": [0, 1, 2, 3]
}
And you asked for level1[0] (Your "Path Preview" is /level1[0]/).
That will get you the value 0. (If you json would actully look like this)
Hope this helps.