Reading through all of this I am left with two main thoughts.
1) The Current DnD Ranger is not Aargon, so stop saying it. I think that is nowhere made more clear than in the OP where it lays out that high-level rangers are supposed to be heavily armored warrior-kings with castles and followers. None of that sounds like a DnD ranger to me. In fact, many of the ranger "classics" would rather gnaw off their own arms than do that.
Aargon is a fighter/Paladin with the Outlander background and some racial skill proficiencies for his divine birth. Yes, he shares some skills with some rangers, but he is not a ranger.
2) I think
@Undrave really hit the nail on the head for me. If we are going to rethink and redesign the ranger, then I think the strongest place to start is by saying "Rangers are the people standing at the Border."
This could simply be the classic Border between the Town and the Woods, like everyone always says. It could be the border between the Underdark and the Surface World, like the Gloomstalker shows. It could be the border between the Outer Planes and the Material Plane, like the Horizon Walker. All of this works.
And, it ties a lot of the ranger's key aspects into a solid purpose that makes sense. Why do Rangers track? Because something got past them, and they need to find it. Maybe it was a child that fell through to the Fey or maybe it was an Starspawn cracking open reality, but the ranger will find them. How do they hunt? It depends on what they are doing. You could have the classic archer, you could have a slightly more heavily armored warden, you could have a fleet-footed dervish. It depends on what they are doing.
But, vigilance, watchfulness, maybe the occasional companion to aid them. Magic because magic is at these borders. It all slides together in a very coherent way, and it gives the ranger a rather unique identity. No body else is holding this role in the DnD worlds, but it makes sense to give it to Rangers and Druids as balance keepers and those on the fringes.