i don't know how to unlock this path!!
You're in the wrong place, get out of the part where you can explore the junkyard. When you have the option to 'Pay a visit to the Rat King', click 'Go down the underground tunnel', then click 'Clear the path'. Get a few energy drinks 'cause you'll get tired a bunch of times. Continue until the path is clear, you should be able to go to the jungle.