"Persons" are individuals. "The people" are a select group of persons, depending in the subject. For example, "the people" in the second amendment were ‘free able-bodied white male citizens’ -- not non-whites, not women, not children, not the elderly, not legal residents, etc. Certainly, not all persons.
"The people" in Article I, Section 2 (The House of Representatives shall be composed of members chosen every second year by the people of the several states ...) were white, male, citizen landowners only. Not all persons.
"I consider this decision fully revealing regarding the meaning of the second amendment by its casual inclusion in the opinion."
Not the second amendment. The second amendment didn't apply (and still doesn't) to the states. At that time, the entire Bill of Rights didn't apply to the states. As you said, he was referring to extending the rights of state citizenship to the slaves.
He said if slaves were citizens of a state, then they would have all the rights of that state -- the full liberty of speech in public and in private upon all subjects upon which its own citizens might speak; to hold public meetings upon political affairs, and to keep and carry arms wherever they went. Those were rights protected by each state, not the Bill of Rights.
"There are many other good reasons, I believe, not explicitly put forth in the second amendment but implied in the concept of defense."
There may be, but every lower federal court opinion (save two) ruled that the second amendment protects the ability of a state to form a state Militia from federal infringement. Each state protects the individual RKBA.
That, sir, is asinine.
You are saying the Constitution respects natural pre-existing rights of individuals, insofar as a government decides which individuals get to be part of a select group. This is doubly stupid because the 2nd Amendment exists in great part precisely to counter those whom you would grant the power to limit those who may exercise that right.
While there were indeed cultural limitations on who were included, over time we have grown more enlightened and seen to it that non-whites, non-landowners, non-males, and to an increasing degree non-adults get to enjoy these rights, with obligatory protection from both federal and state governments (even if the state does not explicitly agree, they are compelled insofar as they are part of a federal whole).
If the feds or state, practically speaking and with due legal weasel-wording, said "roberpaulsen is forbidden from owning any weapons, publishing any verbiage, and we're going to quarter a soldier in his house - because we hereby exclude him from 'the people' who get to enjoy the related rights" would you be OK with that?
There is nothing indicating limitations on "the people" was intended. Insofar as political oppression had excluded some from "the people", that has been deemed wrong-headed and immoral.
The Founding Fathers did not write the Bill Of Rights just so that the government - whatever layer - could conveniently redefine them out of existence.