Yes, PatH., I agree, I did see the tribe reuniting, with new found respect for the elders, as a happy ending.
I Just went to the movie theater on Thanksgiving night with my three grandchildren ages, 5, 8, and 14, their parents (my son and his wife), my daughter in law's parents, and my hubby to see the movie "TROLLS." The theme in this movie was you can find your own happiness from within, not from other people or things you consume, and also to stick together and never leave anyone behind. The father troll said in the early part of the movie, "No trolls left behind!" So he went back to save the youngest of the trolls from those who were going to eat the trolls, thinking that it would bring happiness into their lives. Later in the movie the father has grown old, the daughter is now in the position to save the trolls who have been captured to be eaten, and says to her father she now must go to rescue them. She repeats to him, "No trolls left behind!"
This movie made me think of the ending of this book, where they decide no one will be left behind. Young and old, everyone is important, special and contributes some way in this world. When you stick together you can conquer the trials and troubles in life, and you will find happiness inside yourself.