The character of Harry Potter is not simply a wizarding boy who battles Voldemort. What the author has created through Harry is an age old character device, in that she uses Harry as a symbol of good and his antithesis, Voldemort, as a symbol of evil. This is central in all Arthurian type stories, meaning that they are born from the King Arthur legend, as is Star Wars, The Lord of the Rings, The Hobbit, etc...
Harry Potter represents that king figure, albeit a sometimes hesitant one, as he knows his responsibilities, yet is somewhat reluctantly drawn into the task of destroying that which is ultimately a part of him. This is because Voldemort's death curse on Lily Potter, Harry's mother, fails to kill the baby Harry. This represents the power of love, and love's supreme ability to overcome bad.
As with other "ruler" types from stories such as Aragorn, from The Lord of the Rings, and Luke Skywalker from Star Wars, and King Arthur from L'Morte de Arthur, Harry must heed the call to battle in order to cleanse the wizarding world from the ultimate evil of a purely negative character. The same is true in the above referenced stories, such as when Luke Skywalker must defeat Darth Vadar.
Harry Potter embodies all that is good within a young boy thrown out into a strange world trying to make it on his own. As Harry matures each year in the subsequent books, he transforms into a young man who struggles with all too human feelings as jealousy, reluctance, lack of fortitude, and hasty decision making. Ultimately, Harry chooses to search out the remaining horcruxes in order to destroy Voldemort. Of course, his trusty sidekicks help him along the way in the form of Hermione and Ron.
Harry Potter is a dynamic character who experiences a range of struggles. In youth, he struggles to fit in with the Dursleys, he struggles to fit in at Hogwarts, but once he finds his stride, he definitely takes charge of several situations. He forms Dumbledore's Army, works with the Order of the Phoenix, participates in the Tri-wizard Tournament, and the list continues if you've carefully read all seven books. He learns to use his own strengths, and builds upon his weaknesses, such as when he feels deep resentment towards Dumbledore and his closest friends. He must learn to overcome these emotions in order to fulfill his destiny.
In these ways, Harry Potter falls into the formulaic format of the Arthurian legend story line, which can be explained as the quest for goodness over evil, containing a reluctant warrior figure who finally rises up to defeat the enemy.