there are 4 entities on this screenshot. 3 sprites character, the boss and the floor and the other being the background.

The game mechanic here is collecting the puzzle piece and having the animation feel more interactive to the player. The cannon firing is also 2 sprites the cannon and the cannon ball, the cannon ball doing damage to the player on hit. interactive alders are also shown in this, when player walks towards he is lifted using a second sprite to show him looking like hes climbing it

The game mechanic shown is the player, falling and when its sprite collides with the plat form of spikes it kills the player.

The picture shows multiple things happening at once, the 2 Sprites cannon and cannon ball and the enemies around. The game mechanic here is slowing everything down in the ball thats around the player.