He's 16. I think he said he's like 155 lbs. He looks decent in his RMP thread, he used to be fat.
Ok, so a couple things.
It's fine to push legs hard. I'm sure you see a lot of guys who do things other than legs on their leg days, but if they're not pushing their legs as hard as you are, that would explain why they can do that. Not only do I not doing anything but legs on leg day, I usually don't do anything but squat. A single exercise is sufficient for me. So no, you don't have to bench press on leg day, lol.
If you do want to do more than just legs on leg day, this would indicate to me that you'll likely be training all your muscle groups more than once a week. If you're training legs, or anything else for that matter, more than once a week, definitely back off on the intensity. It's really all about what suits you mentally. For me, I love to push hard in the gym, and this especially applies to my legs. But because I go so hard, I'm not doing it more than once a week. As long as you're making progress, keep it up.
As far as other bodyparts are concerned, it's perfectly normal to see a lot more growth in legs than other body parts, particularly as a young/new lifter. Your legs have so much more growth potential than the rest of your body, so when people start training legs hard alongside everything else, there's a good chance they'll blow up, even if the rest of the body is sort of stalling. That's fine. Your leg development isn't actually hindering growth elsewhere. Just make sure you eat enough and sleep enough to recover from your workouts properly, and you'll keep succeeding.