Explain the rationale for naming the Primary sector as 'Primary'

The Primary sector includes activities related to , agriculture, forestry, mining, quarrying and fishing. These activities form the base for all other products that are manufactured. An example is of a carpenter making wooden furniture.
For this Secondary activity, he will need wood as a raw material, which is obtained through the forestry activity. Similarly, jeans are made from cotton, which is provided by agriculture. This is the reason why the word ‘Primary’ is used for these activities.