The inclusion of myth in the novel is a clue from the author that we should use mythology as a lens for understanding the plot. Although the characters in the story feel existentially confused, the reader has an advantage: By seeing the inherent beauty and existential drama of their story, the reader can answer their questions with a broader perspective. What is the nature of experience? What is the meaning of human life?
The characters would probably say "Those are questions with no answer." But actually, their stories are an answer, in a weird way, because we can learn from their story (as myth).
The mythic value of Raj's experience is that he is a full-blown, undeniable hero. He goes on a journey into the wilderness where he encounters something divine, and he comes back changed, and even though he doesn't have the intellect to explain that to his parents, his parents understand it.
This is actually more universal than it seems. Which parents understand their children perfectly? Because of the ineffable quality of experience, all humans are like Raj, because they are unable to express the true nature of their existence.