1. An idiot savant can unite a nation. Naruto always had that special spark that made others want to follow him even if he wasn't the smartest or most adept ninja, and he had a way of converting enemies to friends even though everyone initially hated, mocked and feared him because of the power hidden inside of him. It seems like a common theme in manga and anime for the main protagonist to be a little thick in the head, probably because it makes them all the more lovable to their audience.
2. A "genius" really doesn't always make the best leader. Look at Sasuke and all of the convoluted ways he tried to lead others and achieve power. Sasuke's motivations were also unclear at times, especially how he changed so easily in his goals--from wanting to kill his brother who murdered their entire clan to wanting to destroy the village that condemned his brother and made him kill his clan to wanting to protect and become the leader of the very same village he vowed to destroy. One of the major antagonists of the series, Madara Uchiha, had a similarly flawed reasoning.
3. Character development is everything. There are some who scoff at the way Naruto and other characters "conveniently" achieved new levels of power before fighting stronger enemies, but for those who paid attention throughout the series, everything in the story flowed together almost flawlessly. Also the use of world building was done expertly with the use of bloodlines, histories, character relationships, etc. to the point that you can't help but appreciate Kishimoto's genius.
4. There are those who are born with talent and those who have to work at it. Straight and to the point, but illustrated perfectly through the relationship of "failures" such as Rock Lee and Naruto and "geniuses" such as Neji and Sasuke.
5. Having a "sun" inside of you perforates the inner darkness and negates the outside influences that would cause you to embrace it. Another common theme in manga and anime is fighting for your beliefs and those precious to you. This is stressed throughout the "Naruto" series, but it does explore one interesting concept wherein the jinchuuriki, such as Naruto and Killer Bee, tame their own inner darkness and the tailed beast spirits that they were tasked with containing by focusing on their "suns", i.e. parents and friends.
While this is only a succinct list of things I learned from the series (and I didn't fully explain the character relationships or points made because it would take WAY too long and I couldn't do it justice), I have a lot to take away from Kishimoto's work. He is definitely one of the primary influences for me as a writer and creator. And Naruto is a character who has taught me a lot about myself, human nature, and the world as it is. Along with Batman and the Teenage Mutant Ninja Turtles (who I may talk about in the future), Naruto will be forever kept in mind and held as a standard for great storytelling. That's all I really have to share for now, but there is always more to come!