I spent 3 decades DRAWING PICTURES of battery cables that had masking tape starting with A for the smallest wire.
Then digital cameras came along and I still took notes the number of wires to each individual battery post.
I have always thought that this was far better than the alternative.
You are faced with the alternative.
Be patient
Find out which circuit does not work before connecting the wires.
Common sense: A 10 gauge wire is inappropriate for a radio and a 16 gauge wire is ridiculous for say a high powered electric jack.
0.xx ohms is a direct connection which can be a dangerous short.
Go buy some alligator clips and a roll of 18 gauge wire and make a meter ground wire Extention. Mystery wires with no potential to the ground can be connected then take your meter or test lights and check the battery terminal on the ALTERNATOR. But make sure you are not confused and think the terminal to be dead while it's actually alive.
I've resolved so many of these issues it wasn't funny. One customer tried to screw me royally by asking me to help. I checked his refrigerator by smell and his alternator by continuity. Boy did he ever get red-faced profane when he knew the jig was up. This isn't the easiest way to make a living.