You are definitely going to have to work in more time for exercise... that's the first step. He's just got too much energy... as the saying goes, a tired dog is a behaved dog. Or something like that, lol.
My little pup is super high energy as well. If she is bored, so is a menace. During the work week I take her to doggy daycare 3x-4x. She loves it there and every time I pick her up she's literally falling asleep in the car home. Sometimes on the nights after daycare I'll take her along for an evening walk/hike with our other dog, but she's also content to just lounge around the house alternating between napping, chewing on her favorite chewie, and trying to get the cat to finally love her. On the days she's not in daycare we go for very long walks/hikes and she gets lots of supervised outside time where I toss toys back and forth for both dogs. She has to be supervised as she occasionally tries to get under the fence to follow a scent, and we can't let that happen even one time, as we back up to a very busy road. On the days she isn't in daycare, if she doesn't get appropriate mental/physical stimulation, she will let us know by chewing something that she shouldn't. Like our furniture, walls, or kitchen cabinets.
If you have a forest preserve or something like that nearby, try an hour long walk there, giving him plenty of chance to sniff and explore. I've noticed with my little nut ball that just a 30min walk in the forest tires her out far more than an hour walk in our subdivision, because there is just SO MUCH to sniff and explore in the forest.
I'm not a fan of people on pet forums telling people they chose the wrong dog for their lifestyle. It's not constructive at all and just makes people feel even worse about their particular situation. As long as you truly care and are actively trying, that is what matters. And you obviously are, otherwise you wouldn't have logged on to the internet, searched for a dog forum, and posted about this in the first place. You would have just dumped the dog. I also think every pet relationship is give and take, as they are ALL different (I have 4 animals in my house, not counting my husband, and all 4 of them are unique in personality and needs). We have to learn what works for our pets, just as pets will learn what works for us. Dogs especially are ALL about routine. If you are consistent and patient they will eventually understand what is expected and become secure in what defines their life.
Just don't give up, and your immediate priority should be to get your dog more mental and physical stimulation. See how things go after that, and decide then if more help is needed, which would be in the form of a professional dog behaviorist/trainer. I do not advise returning or rehoming the dog. You committed yourself to this babe when you signed those adoption forms... and you know you can do it. Trust me, I've been in your shoes before too.
Good luck!