You say that not every contract entered and signed voluntarily should be considered valid, but do not state why not.
You say that government should not enforce contracts, but do not say how they should be enforced. What meaning does contract have if not agreements entered into and bound by the law, each party being able to seek redress in the courts for violation of the terms agreed upon...?
You voiced your support for no restriction on the sale of organs. But you focused in narrowly on this one example, at the expense of the broader principle. If a man can enter into a contract voluntarily selling parts of his body, he can likewise sell his whole body, or a life term of service. If he owns it, he can sell it or turn it over as a term of the contract. At least, you have not demonstrated why, according to these principles, he should be prohibited from doing so.
Toward the end of your comments you invoked the Deity, without elaborating on where or when this deity revealed his opinions to you.
You also claimed that no other man can own your moral right to act. You introduced the morality of the issue into a discussion that had previously referred only to legality and legal capacity to enter contracts. None of the other examples had any reference to whether the contracts entered into were moral or not.