The "We" it was written for were Protestant British & Germanic monied male landowners - the new aristocracy.
The nascent USA couldn't even afford to mint its own money, let alone pay for a standing professional army. The Mexican Peso was legal tender in the US till 1857. It's why we have dollars, quarters, and cents instead of pounds and shillings. The US used to be rather poor. Till it stole half of Mexico.
The Second Amendment has two parts, a prefatory clause, "A well regulated Militia, being necessary to the security of a free State," and an operative clause, "the right of the people to keep and bear Arms shall not be infringed."
The prefatory clause is the why, the operative clause is the how.
Why:
"A well regulated Militia, being necessary to the security of a free State"
How:
"the right of the people to keep and bear Arms shall not be infringed"
Hope this helps!