To get past that part, you have to simply jump over the rubble on the upper path.
Because you can't jump over the first rubble you encounter, you automatically assume you can't jump over the second.
I did the same thing.
Hopefully Rolanda sees this; it'd be worth going back and making that section a bit clearer. Making them boxes, instead, maybe? Make it look like there's a collapsed truck that you can hop over, or something of that nature.