That's not a problem of this perspective, that's an entirely separate issue: The still evolving debate between what takes precedence: Federal powers or State powers?
Sometimes state, sometimes federal. This is why all parties are trying to pack the courts with ideologues of various leanings.
You misunderstand my point. It's not about which constitution takes priority (the answer here is actually very simple: for federal laws, only federal constitution applies; for state laws, the state constitution additionally applies).
The point is that the original US Constitution, as well as the Bill of Rights, was worked on and ratified by the same people who worked on their states' constitutions at that time, and you can, in general, see very clear parallels between state and federal constitutions when it comes to rights. So, given that at least some state constitutions from that same period explicitly spell out individual right to keep and bear arms, I find it dubious that it was not one of the considerations when they adopted the same right on the federal level. The fact that the verbiage of 2A cites militia as a justification implies that this is the one they thought most important, but not that there weren't any others; and, of course, the verbiage doesn't actually condition RKBA on militia membership in plain reading.
There are also letters and other discussions from that time that, on the whole, make it fairly clear that militia was understood as including everyone (and not just those states might choose to designate as such), and that the right was thus really meant to be universal.
Letters and discussions we can dismiss outright. This is always a selective argument based on your leanings, and these are inevitably used to twist what are otherwise fairly clear wordings even in the language of the day. A lot of people said a lot of things, but what matters is what is enshrined in law.
What state constitutions of the day say something different than what is written in the federal constitution? I am interested in looking into it at least.
ETA: I looked into it. Your argument only seems to have Pennsylvania as a leg to stand on, through the participation of Ben Franklin, and even that is flawed according to historians:
Sometimes state, sometimes federal. This is why all parties are trying to pack the courts with ideologues of various leanings.