The number one cause for chewing on thing is boredom. Some people will just keep their puppy in the kennel all day long while their kids are are school and they're at work. I'm homeshcooled and my mom stays home so I dedicated the whole day to training and playing with her. I wouldn't go to take a break until she had been worn out and was ready for a nap in the playpen.
They have about a billion toys of all different shapes, sizes, and textures. I also rotate them every week so they have new and exciting toys. I got them some puzzle games too. Wearing them out with a toy, or by going on a walk in great but they also need mental exercise. Training and puzzle toys that stimulate their brain are important.
I give them about 5 mins of training a day. Keep it short and fun.
To help puppy biting you need to correct it early on. When Rosie bites, or rather gnaws on our fingers, I simply say 'no', and redirect her to a teething toy. This way she know not to chew and what she should chew.
I've never spanked or hit my dogs for unwanted behavior and they now are both very obedient. They are both quite different too, Rosie is very stubborn, and Teddy gets really playful and a bit crazy when there's a reward. Since Rosie is stubborn, I had to find a high value reward, and for some that might be their favorite toy, a certain treat, or belly rubs. Learning whatever motivates them is key. For Teddy, I made him sit and stay, this way he learns to calm down a listen, then he is rewarded. For Rosie I say the command once so she know she has to listen the first time. You have to be patient. When she listens I give her lots of praise with a high value treat. After doing this with them a couple of times they now do great.
Another thing I did with Rosie, we kept her in one area of the house. We don't have any carpet but we do have rugs in the living room and dining room. Our kitchen is in the center of our house with everything else around it. The living room to the left when you come in, the dining room to the right and farther in the house, and the sun room at the back connecting the three. I wish I had gotten baby gates, but we blocked of the the living and dining room with and ottoman and their stroller box as well as a few other things. Yeah, it didn't look the best, but it got the job done. The reason we did this was 1, we didn't want her on the rugs, 2 we could keep a better eye on her as she got older and we let her out of the playpen when even when napping more, and 3, she couldn't get into anything not fully puppy proofed. If you look at some of Zak Georges videos, you'll see him talk about the importance of this often. Here's where he explains it, there's also a lot of other great info
most of the shelter dogs are young adolescent dogs too so it’s like they grew up and were no longer a cute little puppy and got dumped. 
