Murphy is a precious young puppy. We don't come out of the box good to go. Murphy isn't even a teenager yet. Do you have children? I started maturing in my early 30s. lol
If you let Murphy run around jumping all over people, he is learning that lesson well.
As was pointed out, just because he has learned a directive -- like sit for a treat -- doesn't mean he knows the command in all situations. It takes a while and a lot of repetition and proofing to get reliable behavior. If Logan (my Golden) gets a command -- I'll stick with sit -- and he holds the position until released regardless of other dogs, people, deer, or what have you -- that is knowing the command. At this point, he offers an autosit when I stop to talk to people. When he was younger he could be distracted by things like leaves blowing and butterflies.
Anyway, I have not met Murphy, but he sure is a cutie and definitely not an idiot. He is budding potential awaiting to learn. Goldens are fun puppies and young dogs. You just have to stay on your toes. Make learning fun. teach him to engage. It takes time. Each dog is different. Enjoy!