The origin of leather shorts and perhaps as well long trousers is sometimes attributed to the French culotte. The word means still trousers that reach above or to the knees. In former times, even simple pants seem to have been included. Today they are usually called caleçon or – more modern – slip. In the French Revolution, subtly appeared the term sansculottes . "Sansculottes was initially a mocking image, but quickly developed into the common name for the revolting early proletarians who intervened in the revolution".* Instead of the knee breeches worn by the nobility, the sansculottes donned long trousers. Even if the term suggests it – by no means somebody was unclothed! ☺
So far, I have found no evidence in literature or paintings that the culotte was originally made of leather, or even that leather trousers were common in Central Europe. By exception, leather culottes were worn during some time in the French Alsace for hard work in the fields. In general, lederhosen were at that time and are today again native to regions of Austria and Bavaria close to the Alps. Basically, they appear there as endemic plants such as certain Bavarian herbs like the Löffelkraut.
But for about twenty years they had offshoots all over Germany. After the Second World War, leather trousers were initially a mundane addition to the lack of clothing. Their robust properties made them a natural article of clothing in the FRG and GDR, and not only for children and young people. At the beginning of the sixties, blue jeans began to gain acceptance due to the progressive change in the spirit of the age. In terms of durability jeans are nothing to sneeze at. Let us remember the common great-grandparents of leather leggings and linen jeans who, from the 18th century onwards, diligently created modern times in the shape of common work trousers in forest, field and workshop.
* Quote from Wikipedia, "Sansculottes", traduced from the German version