The problem with that approach is, then you could say that 2A only applies to muskets, since they never could have foreseen the wide array of guns we have now.I never claimed that it was. No reason it should have been needed.
Up until recently, everyone knew what marriage was. There is no reason to expect that anyone who had any hand in writing the original Constitution, nor any of the Amendments thereto, would have ever imagined that anything that they wrote would be twisted and corrupted to support a disgusting and immoral homosexual mockery of marriage. If they had anticipated that, then they surely would have chosen their words more carefully to prevent it.
Perhaps they weren't thinking of gay marriage because they didn't need to. All they needed to do was provide freedom for future generations, and the 14A did that.