Porters appeared extensively in the ancient world as "beasts of burden". Ancient Sumerians enslaved women to carry wool and flax. Porters still carry things in many third-world countries, especially where animals (camels, oxen, horses, dogs) or machines (carts, lorries, ships, trains, aircraft) have not taken over their traditional functions.
The term "porter" sometimes refers to airport or hotel employees, but generally refers to relatively menial labor.