You followed the butterfly and now you’re trapped inside the house. You need to get out.
Jump on the board and walk to the left. The board will tip over to the left side. Get off the board, walk to the right and push the crate on the right further to the right so it’s not under the board anymore.
Walk to the left and jump at the shelves three times to make the box standing on top of it fall down. Pick up the BOX and walk to the right. Put the box on the left side of the board then jump up yourself. Pick up the BOX again and walk to the right. Put the box down on the board at the right end so the left end of the board is pointing up.
Walk to the left and since the box is on the right and heavier than you, you can walk up and jump into the elevator to go to the level above. There you’ll find freedom again.
Game source: A copy of the game was found here on the internet.