The world’s first cargo aircraft was born in Germany, called the Arado Ar 232, or sometimes called the Tatzelwurm, designed and built by a German company called Arado Flugzeugwerke. In the World War II.
The design is the first aircraft designed to carry cargo, especially the front of the aircraft, it will extend long and wide to normal to increase capacity and in the way the company has built. The name Junkers Ju 90 V5 at the later time.
At present, the prototype model of Arado Ar 232 is worldwide use in today.
References from https://en.wikipedia.org/wiki/Arado_Ar_232.