I need help identifying wires under the hood

My mom has the vehicle listed above (ltz) that she rarely drives. Yesterday it wouldn't start. I tried to jump it off and still nothing. Although the battery is only a year old I took it out and had it tested. It's good. All of that was done in the dark. The next day upon closer inspection I noticed what looks like squirrel poop on the valve cover and chewed wires behind it. I'm attaching some pictures. Could this be why it won't start?? The lights and radio all come on just fine. But it doesn't do anything no crank no start, nothing.