You have likely got big BIG problems. When wiring burns like that it "crosses" inside the harness by melting insulation and melting two or more wires together. The big wire hooked to the starter relay that is bare goes down to the starter solenoid. I cannot see enough in your other photos to guess. I would just unhook/ unplug pull out the affected harness(s) and nail it down to some scrap plywood. Unwrap it, tying the branches in place, and look for physical damage / melting.
If you don't want to rebuild/ replace all of it AND if it's not too bad, sometimes you can repair them in place, cut out and splice or replace the affected wires.
Wander over to MyMopar and download a free service manual. Some of them there came from the guys on here
Also at MyMopar get yourself one of the aftermarket wiring diagrams on there. These are sometimes easier to follow than the factory diagrams, but are not as detailed