It's usage in common vernacular is "imitations of technology that don't perform the function of that technology." It comes from the Allied campaign in the Pacific during WWII where Americans would give stuff to indigenous people living on islands occupied by Japan. When the Allies moved on to the next island, it was believed people made things like "radios" and "planes" out of wood they thought would bring free shit back to them, despite the objects being fake copies.

What cargo cults actually are is the religions that sprouted up where local cultures had beliefs others couldn't understand because of cultural differences. Sometimes the arrival of American war ships and cargo would coincide with a local prophecy. Sometimes a person like King Phillip is seen as a god due to reasons known only by the indigenous population. Sometimes the conflict would cause speculation of world-ending disaster.

AFAIK the wooden planes thing is less about people with magical thinking the "plane" will bring back cargo and is more of a monument to commemorate when the cargo arrived.