After fighting a long, bloody war against a central government that refused to recognize their rights, the Founders perhaps found it hard to envision their own states violating those same rights. To their way of thinking, the U.S. Constitution was not the right place to protect them from their own state government.
Most, I think, of the original thirteen states had a right to keep and bear arms protected by their own state constitutions.
After the Civil War, however, the thirteenth and fourteenth amendments were passed, recognizing that there were certainly some circumstances under which states WOULD fail to protect the rights of its own citizens.
One example of what I am saying was the Dred Scott decision. At the time, slaves were not considered to be part of the people protected by the Bill of Rights, nor were they considered to be citizens of either the United States or of the state within which they were born.
The Dred Scott decision described the situation that would exist if they were to recognize the rights of Dred Scott; "It would give to persons of the negro race, who were recognized as citizens in any one State of the Union, the right to enter every other State whenever they pleased, singly or in companies, without pass or passport, and without obstruction, to sojourn there as long as they pleased, to go where they pleased at every hour of the day or night without molestation, unless they committed some violation of law for which a white man would be punished; and it would give them 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."
I post this excerpt to make two significant points.
First, at the time of the Dred Scott decision, it was the U.S. Constitution which was flawed and created the injustice for Dred Scott. It was not the Supreme Court. The flaw was corrected by amendment after the deaths of half a million people in the Civil War.
Second, I would point out the words of the decision; "to keep and bear arms wherever they went". The Supreme Court was recognizing the unalienable right to keep and bear arms and gave no consideration whatever to the idea that any state would disarm its own people.
The coming Civil War would provide even more reason why no state would ever consider disarming its own people. Unfortunately, people in some states today have grown so complacently satisfied with the ever-expanding role of government in people's lives that they today ignore the right to keep and bear arms.
There is an effort being organized to have the People's Republik of Kalifornia secede from the Union. Should that come to pass and a new civil war erupt, one of the first things they will have to do is re-recognize the right of the people to keep and bear arms.