Even though the "I" who is narrating The Hobbit hardly ever appears in the novel, this is still technically a first-person book. Someone occasionally steps in to make direct comments on the novel's events. For example, when this narrator introduces Gandalf, he comments, "Gandalf! If you had heard only a quarter of what I have heard about him, and I have only heard very little of all there is to hear, you would be prepared for any sort of remarkable tale" (1.6). So it almost sounds as though there's some live person telling us one among many stories that he knows about Gandalf. This gives the whole novel a chatty (and often hilarious) tone.
Since The Hobbit sometimes sounds like it's coming from on oral storyteller, it contains lots of little side comments about everything that's happening in the novel, and about Bilbo in particular. The narrator seems to have a ton of affection for Bilbo. Even when Bilbo is at his worst, as when he foolishly allows himself to get caught by trolls in the second chapter, the narrator sounds deeply sympathetic about his "poor little feet" that had been "very squashed in [troll] Bert's big paw" (2.67).
And even when Bilbo is at his best, generously weeping for frenemy Thorin Oakenshield after Thorin's untimely death, the narrator keeps up a wry, slightly condescending tone: he reports Bilbo's crying "whether you believe it or not," acknowledging that Bilbo is a "kindly little soul" (18.20). The fact that the narrator never takes Bilbo too seriously makes the hobbit seem even more relatable to us. And the narrator seems to like Bilbo so much that we can't help but join in.