The evolution and maturation of the protagonist, Bilbo Baggins, is central to the story. This journey of maturation, where Bilbo gains a clear sense of identity and confidence in the outside world, may be seen as a Bildungsroman rather than a traditional quest. The Jungian concept of individuation is also reflected through this theme of growing maturity and capability, with the author contrasting Bilbo's personal growth against the arrested development of the dwarves. Thus, while Gandalf exerts a parental influence over Bilbo early on, it is Bilbo who gradually takes over leadership of the party, a fact the dwarves could not bear to acknowledge. The analogue of the "underworld" and the hero returning from it with a boon (such as the ring, or Elvish blades) that benefits his society is seen to fit the mythic archetypes regarding initiation and male coming-of-age as described by Joseph Campbell. Chance compares the development and growth of Bilbo against other characters to the concepts of just kingship versus sinful kingship derived from the Ancrene Wisse (which Tolkien had written on in 1929) and a Christian understanding of Beowulf.
The overcoming of greed and selfishness has been seen as the central moral of the story. Whilst greed is a recurring theme in the novel, with many of the episodes stemming from one or more of the characters' simple desire for food (be it trolls eating dwarves or dwarves eating Wood-elf fare) or a desire for beautiful objects, such as gold and jewels, it is only by the Arkenstone's influence upon Thorin that greed, and its attendant vices "coveting" and "malignancy", come fully to the fore in the story and provide the moral crux of the tale. Bilbo steals the Arkenstone—a most ancient relic of the dwarves—and attempts to ransom it to Thorin for peace. However, Thorin turns on the Hobbit as a traitor, disregarding all the promises and "at your services" he had previously bestowed. In the end Bilbo gives up the precious stone and most of his share of the treasure to help those in greater need. Tolkien also explores the motif of jewels that inspire intense greed that corrupts those who covet them in the Silmarillion, and there are connections between the words "Arkenstone" and "Silmaril" in Tolkien's invented etymologies.
The Hobbit employs themes of animism. An important concept in anthropology and child development, animism is the idea that all things—including inanimate objects and natural events, such as storms or purses, as well as living things like animals and plants—possess human-like intelligence. John D. Rateliff calls this the "Doctor Dolittle Theme" in The History of the Hobbit, and cites the multitude of talking animals as indicative of this theme. These talking creatures include ravens, a thrush, spiders and the dragon Smaug, alongside the anthropomorphic goblins and elves. Patrick Curry notes that animism is also found in Tolkien's other works, and mentions the "roots of mountains" and "feet of trees" in The Hobbit as a linguistic shifting in level from the inanimate to animate. Tolkien saw the idea of animism as closely linked to the emergence of human language and myth: "...The first men to talk of 'trees and stars' saw things very differently. To them, the world was alive with mythological beings... To them the whole of creation was 'myth-woven and elf-patterned'."
As in plot and setting, Tolkien brings his literary theories to bear in forming characters and their interactions. He portrays Bilbo as a modern anachronism exploring an essentially antique world. Bilbo is able to negotiate and interact within this antique world because language and tradition make connections between the two worlds. For example, Gollum's riddles are taken from old historical sources, while those of Bilbo come from modern nursery books. It is the form of the riddle game, familiar to both, which allows Gollum and Bilbo to engage each other, rather than the content of the riddles themselves. This idea of a superficial contrast between characters' individual linguistic style, tone and sphere of interest, leading to an understanding of the deeper unity between the ancient and modern, is a recurring theme in The Hobbit.
Smaug is the main antagonist. In many ways the Smaug episode reflects and references the dragon of Beowulf, and Tolkien uses the episode to put into practice some of the ground-breaking literary theories he had developed about the Old English poem in its portrayal of the dragon as having bestial intelligence. Tolkien greatly prefers this motif over the later medieval trend of using the dragon as a symbolic or allegorical figure, such as in the legend of St. George. Smaug the dragon with his golden hoard may be seen as an example of the traditional relationship between evil and metallurgy as collated in the depiction of Pandæmonium with its "Belched fire and rolling smoke" in Milton's Paradise Lost. Of all the characters, Smaug's speech is the most modern, using idioms such as "Don't let your imagination run away with you!"
Just as Tolkien's literary theories have been seen to influence the tale, so have Tolkien's experiences. The Hobbit may be read as Tolkien's parable of World War I with the hero being plucked from his rural home and thrown into a far-off war where traditional types of heroism are shown to be futile. The tale as such explores the theme of heroism. As Janet Croft notes, Tolkien's literary reaction to war at this time differed from most post-war writers by eschewing irony as a method for distancing events and instead using mythology to mediate his experiences. Similarities to the works of other writers who faced the Great War are seen in The Hobbit, including portraying warfare as anti-pastoral: in "The Desolation of Smaug", both the area under the influence of Smaug before his demise and the setting for The Battle of the Five Armies later are described as barren, damaged landscapes. The Hobbit makes a warning against repeating the tragedies of World War I, and Tolkien's attitude as a veteran may well be summed up by Bilbo's comment: "Victory after all, I suppose! Well, it seems a very gloomy business."