All nostalgia aside, Majora's Mask is one of the most chillingly beautiful games that takes a simple narrative story-line, but morphs it into a collaboration of more in-depth themes, and theories. People have provided numerous interpretations, and when a creation leaves this much room to be analyzed...You know it's good.
Majora's Mask revolves around the simple idea that the world is ending, which ultimately gives us the task of stopping a crazed moon from hitting the world and crushing everything to bits. The characters in this game are strikingly similar though, mainly because they're almost all from the Ocarina of Time, thus showing a relation between two worlds that are actually completely separate: Hylia, and Termina (termina meaning "the end" or "terminal"). Due to this relation, people have provided insight for many different reasons for the familiarity: It's all a dream, Link is dead in purgatory fighting for one more chance at life, or, Termina is a parallel universe. Evidence is fitting for each "theory", although I find the one about Link being trapped in purgatory to be most fascinating. There's a really great video on YouTube that analyzes this further. Watch it here.
With the idea of death in Majora's Mask, the Stone Tower Temple plays an amazing role, as it alludes to the Tower of Babel, the tower that man tried to build to reach heaven. In Majora's Mask, Link ascends to the top of this tower in order to receive the "light arrow".
Another intriguing idea that was introduced from Ocarina of Time up to Twilight Princess was the idea that Link is the the "spirit of the hero of time", or the Stalfos that we meet in TP. He says lines we've heard before in Majora's Mask, and could directly tie with this idea that Link did indeed die in this game title, therefore showing the significance of the transcendence of death.
This game title is a genuine masterpiece. As a child, there are many concepts and themes that are overlooked, so I ask for you to play it through once again if you haven't and if you love it as much as I do. The complicity of the game is actually rather fascinating for such a simple idea, and if you do some searching, different theories (endless theories, really) are available. Enjoy!