Owning the land is the most important aspect about owning what is on top of the land. I'm pretty sure the British Owned the land. A trivial point anyway.
The Question remains, do people have a right to to "dissolve the political bands which have connected them with another and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them "?
Or do they not?
The God-given right of rebellion is immutable. Of course winning is crucial to ones continued viability. The colonists won their rebellion. The confeds did not.
The south could have tried secession - no not the phony “spit in your eye” unilateral secession, but true negotiated withdrawal. Instead they had a national tantrum and started a war they could not possibly win.
No, our nation isn’t like a trite song that treats us like inmates. But it isn’t like a magazine subscription that we can ignore and walk away from any time we get a bee in our bonnets.