How Does Relative Surplus Value Affect Production?

Under capitalism, so the story goes, what you have is a mass of free people who are selling a commodity. And that commodity is their labor, or that they are selling to a an owner of property,. The capitalist then uses that labor, that commodity, to earn them more money. So in order for capitalism to be capitalism, and not, for example, serf labor, or feudalism, or any other kind of economic system, it demands amass of free people exploited in the production of commodities. What we see today with wealth isn't every single economic system - i can't call them all 'capitalist' But if there were other forms of exchange, such as those like slavery