Please Help me Understand Gondor Stewardship and Kingship

[Zigûr]

Originally Posted by R.R.J Tolkien

Very good and thank you. Question, so the King of Arnor rightly also is king of Gondor? but the king or steward of gondor not the rightful king of Arnor had it survived.

If I understand correctly, it's a bit complicated. The heir of Elendil was High King of the Dúnedain. So while Isildur was, after Elendil's death, King of Arnor and High King of the Dúnedain, at a certain point he gave the Kingship of Gondor over to his nephew Meneldil, Anárion's son. Afterwards, the Lords of Gondor would claim that the King of Gondor had to be descended from Anárion since Isildur gave the Kingship to Anárion's son.

Therefore, unless I'm mistaken, the reason Aragorn was able to claim the kingship of Gondor as well as the High Kingship and kingship of Arnor was because he was descended from Arvedui, King of Arthedain, and Fíriel, Arvedui's wife, who was the daughter of King Ondoher of Gondor. He (and the other chieftains of the Dúnedain in the North before him) were thus descended from the royal families of both kingdoms, from both Isildur and Anárion. (The kingship could pass down through both male and female lines; that was Númenórean tradition, hence the Ruling Queens. The Dúnedain of Middle-earth had simply ceased to observe it – as came up when Arvedui tried to claim the throne of Gondor himself).

Incidentally it seems that after Isildur's death the "High King" position stopped being used until Aragorn restored it. Maybe it was because the Kings of Arnor by that point had no power or influence over Gondor and the wider Dúnedain people. It seems this was something Meneldil desired, as he hoped that "affairs in the North would keep them [Isildur and his sons] long occupied." (Unfinished Tales)

Then again maybe I'm overcomplicating it and by claiming the High Kingship Aragorn was able to just take back the rule of Gondor as the High King of the whole Dúnedain people.

EDIT: I might also be partially wrong about my "the Steward lacked the spiritual authority" thing, because Cirion called upon Eru at the swearing of the Oath of Eorl as the King's representative. Nonetheless Letter 156 suggests that the Steward did not hold the same "priestly" position as the King.