The core question of "Spiderman 2" is: "Who am I?" Peter Parker, aka Spiderman, has a crisis of identity. Parker's decision to ignore his true identity fails to suppress what is really in his heart. Ultimately he accepts who he really is, thus finding meaning and purpose in life. And joy.
Spiderman 2 illustrates the ancient truth that, until one discovers their real, essential identity, there is no meaning and purpose to life. Atheistic existentialists like Sartre and Camus realized this, and were led to despair. This is because, for them, instead of there being any ultimate meaning to persons, persons create their own meaning. Putting this in existentialist terms, instead of essence preceding existence, existence precedes essence. Persons create their own human nature through free choices. On atheism persons do not have an "essence" independent of their existence. So, one has to invent their own essence.
This is what Peter Parker does in the middle of Spiderman 2. He tries to walk the existentialist walk by creating his own life-meaning to the tune of "Raindrops Keep Falling On My Head." But this fails. Ultimately he cannot deny his true, given nature. He only needs courage to accept who he is. Parker's return to meaning and joy lies in rediscovering his essential being that precedes existential being.
As a theist I believe every person has a God-created essential being. Persons are created in the image of God and, as Augustine wrote, are "restless until they rest in God." This is also the thesis of Rick Warren's book The Purpose-Driven Life. Spiderman 2 illustrates the great truth that our hearts will remain restless until they rest in the essential being that God has created every person to be.