She is a puppy - even an OLDER dog - would behave like this because guess, the dog sees you 24/7 and those strangers are indeed new toys.I still feel like I'm just taking care of someone else's dog and it's already been a month having her. Maybe it takes longer to get that connection? I'm really tired and feel like my patience is at the limit. All totally normal, I'm sure...
And all dogs are different.
My Fina, I've never had a stronger bond with a dog than her, was not typical in displaying her affection. She was, despite being a collie type, an independent dog and her affection was different. It wasn't unusual for her to grab my hand and start "mouthing" [which to the average person is ill behavior] the moment she laid eyes on me... she didn't get overly excited and wriggly and rarely would she wag her tail for anyone. Nor would she come seeking pats and belly rubs, she was much like a cat in her mannerism in that you had to earn her affection it wasn't a given. Most people called her a standoffish dog which I almost always ended up bursting into hysterics about because that was hardly the case.
I'd like to know how you're training the pup though. Most pups don't treat training as a "chore" unless it is boring - too repetitive - or there isn't enough reward to it.