When is a maze not a metaphor, right? Its very purpose in a literal sense is to confuse and obfuscate—to cause you to get lost and disoriented. In the case of our story, the Maze serves as a physical representation of what it's like to be a teenager, and more specifically to be a teenager in the Glade.
For the most part, any maze can be seen as a symbol for life. There are sections where you see an opening and follow it, but you inevitably hit a dead-end and have to retrace your steps to start over. There are straight paths that make you feel like you're in the right direction until you smack right into an obstacle, and there are times where you feel hopelessly turned around and can't figure out which way to go or which way you've come from. There are always moments like this in life, particularly as you get older and your decisions have more impact on what your life becomes.
What makes this Maze particularly difficult is that the walls are constantly changing overnight. In our extended metaphor, this is like trying to follow a difficult path in life and then having the rules you are following abruptly (unfairly?) changed. Wouldn't it be really frustrating? Isn't it kind of similar to how life as a teenager feels? One minute you feel like you've got things figured out and the next you realize everything is completely changed, right?
Sometimes the reason you can't figure out all the answers to life is because there might not be any (oooh, deep). As Newt explains:
"Out there's the Maze […], everything we do—our whole life, Greenie—revolves around the Maze. Every lovin' second of every lovin' day we spend in honor of the Maze, tryin' to solve somethin' that's not shown us it has a bloody solution, ya know?" (6.22)
For the Gladers, too, the Maze isn't merely a place to get lost but also a place to die. Haunted by lethal booger-monsters, take a wrong turn and you could be staring death in the face. However, it is a necessary part of learning about the Glade and how to escape: the boys must face the Maze and all it represents in order to discover the exit into reality.
Your path in life can be the same way: a confusing, disorienting trail that you follow in which every decision could mean life or death, happiness or helplessness.