Oh boy! There's too many things about TLK that I love, but I would have to place its story at #1.
Like any celebrated movie, it has to have an emotionally compelling storyline. Therefore, with its powerful storyline, the audience can care about the characters, and the circumstances they must overcome. Because TLK is a musical, if the film didn't have the storyline it has now, the music wouldn't have much meaning even though it's there to deepen the characters and story in which regular dialogue cannot do. The film's animation is a bit irrelevant to the storyline because anything well drawn can have a clumsy, illogical storyline. See
Cars 2 for an example of this. Although, it is nice to see hand-drawn animation at its finest. So, therefore, pretty much everything in the film that makes it great is because of the compelling plot.
What I love most about the plot is that it carries the universal message about taking responsiblity, and finding one's place in life, which makes it's relatable with everybody. I also find it pretty amazing the wide range of story material the filmmakers received inspiration from, which includes the Joseph and Moses in the Bible, William Shakespeare's
Hamlet,
Bambi,
A Hero of a Thousand Faces, and much more. In addition to this, TLK's storyline somewhat took place at one time in world history; see
The Epic of Sundiata . Third, I love how the story manages to balance its Shakesperean-inspired drama with the film's comedy filled with slapstick and pop culture references thus making it appealing to all ages. The only thing I don't like about the story is that Disney marketed it as being "original" when being initially released, when they knew it wasn't.