The concept of our constitutional form of government is quite compelling, and it has led to the most prosperous eras ever. But that is not to say it's not flawed. In fact, the constitution is all but meaningless now. It does very little to restrain government.
The prosperity achieved was a double edged sword. Because is was realized with a powerful central government in place, it allowed the federal government to amass an empire of unimaginable scale. And as history demonstrates, this is never a good thing. The result has been less freedom domestically, reckless economic policy that will eventually unravel, and a foreign policy that is devastating for large parts of the world.
To a more specific point, I believe we have innate rights because of our self ownership. We are the sole owners of ourselves and no one can justly make a higher claim on us. It follows that we own the products of our labor.
It is completely acceptable to delegate certain responsibilities to others. But it has to be done on a voluntary basis. We are born into this world, without consent, within certain jurisdictions by mere chance. It is preposterous to assume that because we live within certain imaginary lines drawn up by stranger, that we have somehow consent to their rules, monopoly services, and taxation.
Some people might have no problem paying into a system and supporting the activities of their rulers. That's fine, but not everyone consents. And no percentage of the population can ever justifiably initiate violence against the rest of the population.
Morally speaking, you are correct, the government (or any group) cannot justly do anything an individual cannot do. Murder is still murder when done by a large group of people. And theft is still theft when carried out by any number of people and given another name, like taxation.
The problem is, the government, as it currently is, does not operate this way. And the constitution does very little to restrain it.
I was pointing out that the original intent of the framework documents was to severely limit the powers of government.
Since we all have rights which come from natural law (or a Creator being, depending on your worldview) and we have only lent those rights to the government on a limited basis in order to accomplish very limited outcomes; that those rights are very moral and ethical. Since those rights are moral and ethical and the loan of the rights is also moral and ethical and the intending limited use and outcome of the loaned rights is ethical and moral; it also true that the original documents are useful in defining the very limited and very specific ways in which a government can impose constructs on society.
Those constructs cannot allow the government to do anything that the individual cannot do for themselves on their own. For example, I have the right to self-defense and I can loan that right to a government for my defense also. I do not have the right to an unprovoked attack on another person, therefor I cannot loan the government a right to do so on my behalf.