Wrong. A prefatory clause gives an example of why the operative clause is true. It could just as easily read, "Carrots are required for good health, the Right of the people to keep and bear arms shall not be infringed" and still be both grammatically and logically true.
Everything else in your screed is an often used attempt to tie RKBA to militia service. This is backwards. We need the Right because it makes forming a citizen militia easier, however the Right is not predicated on suitability for militia service alone.
The first Congress purposely changed that. The second amendment made clear that we moved away from the English armory and to the personal ownership and possession of any arms that an army might deploy against the People.