Okay, so basically, I think the person below is incorrect or doesn't have a complete answer
Here is the complete answer (With evidence from the book!):
The theme is your heart can be more powerful than laws. The author believes that the law of the heart is stronger. The boy learns this throughout the book. The heart is what makes the boy go back to his pack and save his own life. It says, ‘“Lead us again, O Akela. Lead us again, O man-cub, for we be sick of this lawlessness, and we would be the Free People once more.”’ Basically, this means that without law, they are not the Free People. They would like to be Free People once again and to not hunt freely. Free People should always have a good leader that never breaks the law, so I think the laws of the heart is stronger. Also, if Mowgli didn’t have a heart, I think he would have not killed Shere Khan and left him for the wolves to kill.
