Luggage of the Gods!

Luggage of the Gods is a 1983 American comedy film. In the movie, cavemen living in a mountainous region of Latin America are completely disconnected from the modern world. They speak a simple constructed language, similar to that used in the 1981 movie Caveman. They worship and greatly fear airliners that regularly pass overhead. Tradition in the tribe dictated that they avert their eyes whenever a plane flies overhead. One day, an airliners cargo malfunctions, causing it to jettison a good deal of luggage. Two young male cavemen break the taboo against looking at the planes, and observe the falling luggage. When they leave the tribe, they find clothing, cassettes, and counterfeit paintings, which wreak havoc on the power structure and economy of the tribe. Events get even more out of hand when the counterfeiters come looking for the paintings.

Source: Wikipedia