What you just mentioned is the absurdity of all states, though - no one ever gave their consent to be ruled by a state at all.
Well,
someone did...either via agreement, or acquiescence.
See, the thing about our forefathers was- they were so friggin' high on the idea of having thousands of acres of "unowned" land to claim, that they didn't make very intelligent or ethical decisions, and were easily led on by people who promised to protect their "right" to do whatever they wanted.
Just imagine you get on a boat and land on a giant continent and are told, just take your pick, you can do whatever you want. People went beserk, and then they were all afraid of the beasts (fauna) and savages (people) which were indigenous, so they supported anyone who would protect their land and cattle and sought to "tame" the entire contient with wheat fields, as such.
And of course, at the time, slaves were merely livestock...they didn't really see them as men, but as the missing link between monkeys and white people. So, whatever rights they gave to animals they gave to slaves. And then, all the sudden immigrants started pouring in from other parts of the world (not just white people), so ppl got real nervous because the land is for white people...they didn't want it to be a china or a mexico...they wanted it to be the best version of white culture.
This was supposed to be a white country. People still believe that it is.
It didn't get off to a great start (ethically) so now it's tripping on itself trying to make up for previous missteps. Unfortunately, it's not doing a good job...but on the bright side, people are more aware of their rights (as humans) than they once were (even as they are being taken away).