Nonsense. All contracts have terms. When you agree to those terms, I guess you could say you've "given up your rights," but it would be a particularly worthless characterization. The reality is that the employer gives up rights: they grant you various conditional waivers to use their property, equipment, etc., as well as an obligation to pay you. If you refuse to comply with the conditions of those waivers, they can revoke them and kick you off their property.
To pretend that that's some sort of slavery is insane. The difference between a slave and an employee is that you can quit. Slaves can't quit. Employment without terms and obligations is a fiction that only exists in your fantasies.
The term is indenturement, look it up.