> Not to mention they're just some random people, nation building or not. No rational reason to treat their work like some higher command centuries later.
We treat their work "like some higher command" because it literally is that. Their work (the Constitution) creates a framework that overrides anything enacted by contemporary legislatures. The reason that's so important is because we often (usually?) don't agree on what rules should be. America has large numbers of people who think guns should be banned completely, and also large numbers of people who think teachers should carry firearms. The Constitution is a meta-rule that mediates those disagreements. Of course, to the extent we don't like any particular meta-rule, we could amend it with a 2/3 vote. We don't do that because we don't agree on what the alternative meta-rule should be!
It's entirely rational for everyone to adhere to those meta-rules. Democrats in New York can't just decide to ignore the Second Amendment because once that's out the window, Republicans in Alabama have no reason to respect Roe v. Wade. Everyone tries to interpret the rules to sanction their specific approach, but declaring that we can just decide for ourselves what the rules will be, without reference to the meta-rules, would lead to total breakdown.