Child of light is so fluid. Really liked the flying animations. The fight animations feel a big rugged though, but animations & movement in the rest of the game are very nice as are the lovely watercolor looking graphics.
Memoria, Chains of Satinav & I believe even Deponia created & animated the characters in some 3D program, then exported & painted over them with zBrush from what I recall Simon or David telling me.
Interaction isn't that complicated mate, but it does take a bit of planning. Say for example you want your character to take something from the wall & you actually want to animate the character physically taking the object from wall to hand to pocket/bag/hat, then you are going to need to figure out the scale % the character will be at the interaction point then you are going to need to scale up/down the item that's on the wall in the characters animation frames so that it doesn't randomly end up looking like a miniscule or gigantic version of whatever it was you just picked up. It helps if the artist/animator can mess around with the scene a bit so they know first hand how something looks.
A lot of the old point & click games actually put effort into animating everything. Take a look at Simon the Sorcerer or Broken Sword. Everything was animated. Broken Sword 5 on the other hand.