Walking around a room / depth effect in paper 2D


I’m trying to create a point and click style adventure, I need the character to be able to move around the floor. But I am struggling to make a character move in the Z Axis (I think the Z is what I need) to create the illusion of depth in the room.

I have it so the collision layer is lower than the sprite so it looks like the character is in the centre of the room, I just can’t move up and down it.

Is there anything I’m missing?