No, I haven't shut out the prefatory clause. I do suggest any of the free online reading comprehension courses you can find using your favorite search engine - both for understanding my post and the text of the 2nd Amendment.
The prefatory clause gives a reason why the government cannot infringe on the right to keep and bear arms, not why the right exists. It says nothing at all about why the right exists. If you want to know why the right exists, I refer you to the Declaration of Independence:
“We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator [not man] with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. That to secure these Rights, Governments are instituted among [not over] Men, deriving their just powers from the consent of the governed [not the government].”
The right to keep and bear arms stems from the very first right - the right to life. If a man does not have the toolsor ability to defend his life, including every tool that might be used by those who might want to take his life, then his right to life is void and becomes nothing more than a privilege granted by the government.
Even if the 2nd Amendment is repealed, the right to keep and bear arms stands and is protected from Federal infringement by the 9th and the 10th Amendments. Even if both the 9th and the 10th Amendments are repealed, the right to keep and bear arms will exist.
In fact, every human being on earth has the right to keep and bear arms. It is a right of the Chinese. It is the right of the Uyghurs. It is the right of the North Koreans. And it is the right of every American. Governments can, by force, infringe on the right and use the force of their own weapons to compel compliance, but they can never take the right.