1. It's easy to be fooled by shiny things.
Tamatoa created a liar filled with shiny things simply for the purpose of tricking fish to enter and become his food. He too experiences a lesson in how easy it is to be tricked by shiny things when Moana distracts him by covering herself in glowing algae so Maui can grab his hook.
2. Listen to your heart and follow it wherever it may take you.
Moana always felt the ocean calling her name but it wasn't until she finally listened to it that she was able to learn why it had been calling her and where it was taking her.
3. Face your fears.
Moana itself teaches this lesson in nearly every scene but I think it is best demonstrated when Moana continues to go back to confront Te Ka, the goddess of fire, with the desperate hope of being able to complete the task the ocean had given her. Maui also faces his fears in this scene as he comes back to help Moana after previously saying that he wouldn't.
4. If life knocks you down try again and again until you can stand tall.
Maui was certainly feeling defeated numerous times throughout the movie but he kept getting back up and eventually became the strongest and best demigod he has ever been.
5. The ones we love never leave us, their lessons last forever.
Grandma Tala dies, it is by her faith in Moana and the lessons she has taught her that Moana is able to finally follow the call of the ocean. Grandma Tala said she wanted to come back as a stingray, which she did just when Moana needed her most.
6. When you make a mistake, fix it.
Maui made the fatal mistake stealing the heart of Te Fiti because he thought that would make the humans happy. Instead, he ensured the destruction of the ocean and all of the islands that inhabit it. Thankfully, Moana came along to teach Maui about the error of his ways and help him to fix the damage he has caused.
7. Never be afraid of being different.
Grandma Tala tells it best; she was never afraid of what other people on the island thought of her and the ways in which she lived her life differently than the them. She simply did the things that made her happy and tried to teach others to do the same.
8. All we all really want is to be loved.
The reason why Maui took the heart of Te Fiti in the first place was because he wanted the love and approval of the humans and he felt that that was the best way for him to receive it. Maui's parents abandoned him as a child so he was always desperately searching for love because it was so absent from his life.
9. You are stronger than you think.
Before embarking on her quest, Moana knew nothing about sailing let alone working with a demigod to return the heart of Te Fiti. However, she learned that she was far more powerful than she could ever had hoped to be as she persevered through every obstacle. Although there were times when she wanted to give up, at one point she even did, she always somehow found the strength to continue working towards her goal.
10. Kindness is what brings the world to life.
Moana showing Te ka kindness and compassion is what led to Te Ka returning back to Te Fiti, the living mother island and restoring the world to it's beautiful and fruitful live.