I guess they started with something to offer... we now have cloud feudal "lords", who started by offering services, and then make you follow their altering terms and conditions, who they can change and all you can do is pray that they don't alter it any further. Just like real feudals, the cloud feudals can one day decide you did something wrong, and there's no trial, just direct banishment.

Even worse if your income depend on these feudals (e.g. all the gig-workers who are working without the benefits that exists with an employer-employee relationship).

But to answer your question, I guess it would've started with cooperation between friends/neighbors, the "alpha" person would've led the group of people in some sort of enterprise, his son became the next leader because that's how that was done, this enterprise got bigger and stronger that it encompassed land and resources, and people would want to work for them to earn a living. Heh some even owned navies and colonized places half around the world (the various East India Companies), some are content to work locally (various Mafias).