Alvey, I doubt your derailleur is destroyed, but it definitely needs to move! If you don't know, that hook part with the slot is called the derailleur hanger and the slot belongs around your rear axle , held by the nut. There are plenty of pics, on the web that show what that should look like as well as pics, that show proper routing of the chain through the jockey wheels. Is it a Junior bike (24 inch wheels)? looks so in the pictures. Also, feel free to ask questions here. Have fun with it.