The respiratory system is made up of multiple organs, saying that the lungs is the only required organ is very wrong. While the lungs are probably the most important part of it, the organs that transfer the air are definitely necessary for everything to work.
The main organ that is needed for air to flow from the mouth to the lungs is the trachea, or the windpipe. This connects the back of the mouth to the lungs, without this, no air could get into the lungs, thus rendering them useless.
