Answer:
Basic industries don't depend on other industries to exist; their raw material is not the output of another industry, but rather their raw material is the stuff of nature itself.
The list of basic industries is short. Agriculture, ranching, fishing, forestry, mining, and petroleum constitute an exhaustive list. These are industries that a person 6,000 years ago could perform, using only the body and the resources freely available in the environment (though such people would be unlikely to want petroleum).
By contrast, watch-making requires that an industry of metal-working already exists. The industry of metal-working, by turn, wouldn't get very far unless the industries of mining and forestry (for heat) existed. But mining and forestry don't necessarily depend on other industries for their inputs.
This doesn't mean that basic industries can't be improved by using tools that are fashioned by other industries. The key issue isn't what tools may be used, but what is the raw material for the industry. If nature or natural products are the raw material, the industry is basic. If the raw material coming in to an industry was produced by a previous industry, that industry is not basic.