Primitive man used only that which was close to him on the surface of the earth or in a shallow depth of water. They did not know how to explore the bowels or great depths, to develop fossils.
They gathered vegetation for food, used trees for bonfires and construction of dwellings, made tools and the same building materials from stones.
You can’t do without water, especially fresh water. Also, aquatic inhabitants and terrestrial animals were used for food, clothing and household utensils.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.