I'd be careful of making any conclusions of behavior if you remove the animals from the natural environment.

I've semi-wild street dogs in that really are not that interested in any new toys that are around the house, but they are clearly following and learning from each other on other things. I'd say this is one of the traits they have in common with us.

What they are mostly concerned is food, sex and fighting over territory with other dogs. When the puppies play the main function of it seems very clear to me (future battles). The dogs belonging to the same pack do not often fight each other since the established hierarchy is rather clear.