Marx's Discussion Of How Labor Creates Value

In chapter eight Marx is discussing how labor creates value, where a laborer works within the capitalist labor force. When a laborer performs the tasks necessary to complete a product and add value to that product, the laborer is simply performing the roles that capitalists gave them. It creates commodities that are sold that make a profit, the basis of a capitalist system. Marx later speaks of labor preserving value, which to my understanding is his explanation of how labor is already in raw materials and the means of production helps with the creation of the end product. The laborer maintains the values of the consumed means of production, or transfers them as portions of its value to the product.
In chapter nine, Marx talks about the extraction