system
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human
[LOTR] Why did nobody question Aragorn's heritage?

He seems to have been what amounts to an unknown bum before he came out and claimed to be the heir of the most important kingdom in middle-earth. So he has some minor healing powers. A lot of people in ME do, that doesn't prove much. The most important person who vouches for him is an old wizard who obviously has political interests.

Even Boromir only questions whether Gondor needs a king, not that Aragorn is the reightful heir to the throne.
Surely there were people who were interested in keeping the current governmental structure of Gondor the way it was.  

Where were the Aragorn birthers?
gpt
For one thing, he was raised in Rivendell, so there are elvish authorities who can vouch for his identity. For another, Aragorn clearly has the air of the old Numenorean kings. Consider how Eomer reacts to him when the two first meet:

> Aragorn threw back his cloak. The elven-sheath glittered as he grasped it, and the bright blade of Andúril shone like a sudden flame as he swept it out. ‘Elendil!’ he cried. ‘I am Aragorn son of Arathorn, and am called Elessar, the Elfstone, Dúnadan, the heir of Isildur Elendil’s son of Gondor. Here is the Sword that was Broken and is forged again! Will you aid me or thwart me? Choose swiftly!’

> Gimli and Legolas looked at their companion in amazement, for they had not seen him in this mood before. He seemed to have grown in stature while Éomer had shrunk; and in his living face they caught a brief vision of the power and majesty of the kings of stone. For a moment it seemed to the eyes of Legolas that a white flame flickered on the brows of Aragorn like a shining crown.

> Éomer stepped back and a look of awe was in his face. He cast down his proud eyes. ‘These are indeed strange days,’ he muttered. ‘Dreams and legends spring to life out of the grass.’

On top of this, Aragorn was an enormously popular war hero who saved Minas Tirith from Sauron's armies when he showed up with reinforcements from the south. Some might also have recognized him from his earlier days as an extremely successful captain of Gondor, when he was operating under the alias "Thorongil". Then with Denethor dead and the two next-most-powerful people in Gondor (Faramir and Imrahil) firmly in support of Aragorn, it makes sense that he was able to take the throne with little controversy.