Are all members of the militia people or are all people members of the militia? Do I have a right to keep and bear arms because I am a person or because I am eligible for the militia?
If I am too old for militia duty, or say, wheelchair bound, do I still have the right to keep and bear?
When the second amendment was written, it protected the right of "the people" to keep and bear arms as members of a well regulated state Militia from federal infringement. "The people" were a select group of persons -- the enfranchised body politic; white, male citizens.
"Do I have a right to keep and bear arms because I am a person or because I am eligible for the militia?"
You have the right to keep and bear arms because you are a person. That right is protected by your state constitution.
If you are a member of a well regulated state Militia, then your right to keep and bear arms is protected from federal infringement by the second amendment.
"If I am too old for militia duty, or say, wheelchair bound, do I still have the right to keep and bear?"
The right is not removed. You retain it. If you no longer serve in the Militia, the second amendment no longer protects your right. Your state constitution will protect your right.