> We got the dog to be active with the family
You got a PUPPY, not an adult dog. If you want a DOG to be active with the family you either get an adult dog from a rescue centre/breed rescue, (that way you can see how playfull it is), or you get a PUPPY and put in 2-3 years of hard work of trainng & socialisation and see what you get at the end of that.
The playfullness of an adult dog will vary between breeds, but will also vary between individual dogs, just because you choose a breed that is generally playfull, does not mean a puppy will definately be playfull.
As others have said, puppies spend a lot of time sleeping, on top of this they need time to adjust to thier new life and may be too insecure to 'do' much else other than watch things going on.
As pup becomes more adventerous and more energetic (which will still be only in short bursts for a while yet), he will have much to learn about how he
should be playng with the kids, so it's not wise to allow free play between pup & kids anyway. Children bring out the 'worse' in pups, as they are so much more exciting than adults, they really encourage pups to do all the things we all strive to illiminate through training!
Puppies know only thier instincts, it's thier instinct to play by biting,mouthing, chasing and jumping on thier play-mates (which includes the kids!!), it's up to the owner to teach
how you want pup to play and that play-biting is not appropriate (this in itself should be addressed correctly, read
'the bite stops here' for advise you will be needing very soon).
After all said, I agree with the last poster, if you are allready considering taking back this little pup, it may well be a good choice. Training is so very important and requires so much effort, commitment and trust that a good bond with pup really is important
(I'd imagine it's very hard being comitied to consistant training for 2-3 years when you have no bond with pup).
If you feel like this pup is not entertaining enough, then I fear that bond is not likely to happen and it would be best for pup to go back to breeder while still young, so he has a great chance of going to a family that will understand HIS needs and love him like he deserves.
There are many adult dogs in rescue that would love to part of a family and play, maybe this would be a better alternative.