what is his role in these stories?
Was a hobbit .
The Hobbit
"The Hobbit" is set within Tolkien's fictional universe and follows the quest of home-loving Bilbo Baggins, the titular hobbit, to win a share of the treasure guarded by Smaug the dragon. Bilbo's journey takes him from light-hearted, rural surroundings into more sinister territory.

how old was bilbo when he found the ring 60 years old. does he appear in any fictional work? The title character and protagonist of J. R. R. Tolkien's 1937 novel "The Hobbit", a supporting character in "The Lord of the Rings", and the fictional narrator of all Tolkien's Middle-earth writings.
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The Hobbit [SEP] Introduction
The story is told in the form of an episodic quest, and most chapters introduce a specific creature or type of creature of Tolkien's geography. Bilbo gains a new level of maturity, competence, and wisdom by accepting the disreputable, romantic, fey, and adventurous sides of his nature and applying his wits and common sense. The story reaches its climax in the Battle of Five Armies, where many of the characters and creatures from earlier chapters re-emerge to engage in conflict.