Just curious about what you mean by passive.
As far as spaniels and cavaliers being active well... maybe because I've lived with all three, they just light up for their people. The foot slapping play, the ode to joy body wag as their person walks in the door, it all smacks of the spaniel group to me. I've never met a group of dogs quite like them and I don't consider a papillon an outsider. JMHO
There will always be dogs of varying activity level and temperament throughout a breed. Personally I look at the temperament of the dogs I have, and have met and ask myself how are they the same and in that I see the papillon as very much behavior wise a spaniel. Exactly alike- no, just as there will be variation between every breed. I don't see them like a mini border collie or sheltie. They are much softer temperament wise than I see the average herding breed although the drive levels can be high - above average just like pretty much every active american cocker I've owned under the age of 10.
All my opinion of course...