I'm a free market guy, and I also agree with certain notions of contract law - like you cannot sign away your inalienable rights. You have those rights regardless.
Also, in order for a contract to be enforceable, there must be an exchange of value. I would agree with the validity of a non-compete clause if there was specific compensation tied to that. For example, "we'll give you $50,000 after you leave the company if you don't compete with us for a year." But tacking it onto an employment agreement, no.
The original inalienable rights -- life, liberty, and happiness -- aren't inalienable because their transfer is prohibited by law, but because they're impossible by fact.
You can be denied of your life, your liberty, and/or your happiness. They cannot however be transferred to another person.
Your material possessions -- real estate, chattel property, intellectual property -- can be.
Again: the nature of inalienable rights is intrinsic, not protected by law.
You'll find that meaning supported in the definition you've provided.
(There's a whole 'nother discussion of rights-based arguments generally I won't get into, though I find the question somewhat problematic.)
Also, in order for a contract to be enforceable, there must be an exchange of value. I would agree with the validity of a non-compete clause if there was specific compensation tied to that. For example, "we'll give you $50,000 after you leave the company if you don't compete with us for a year." But tacking it onto an employment agreement, no.