First, I see obvious similarities between “Numb” and The Crucible. Conformity, religious dogma and stubborn tradition rule Salem. There is no room for thinking outside the box or any kind of individualism in a town so strictly governed by mindless adherence to their (hypocritical) religious ways. This loss of individuality is analogous to the feeling of numbness in the Linkin Park song. If individuality or a general sense of self is not there or not acknowledged by others (Salem) or another person ("Numb"), it doesn’t exist. It is numb. The conformity in Salem is analogous to the undertow in “Numb.” When you are forced to conform to a role society has prescribed for you (Salem) or the way someone wants you to be (“Numb”), you lose the sense of your genuine self. “I’m becoming this all I want to do/Is be more like me and less like you."
The Simple Gift and The Pursuit of Happiness are about self-reliance and the ability of the individual to overcome external forces, historical forces and the inequalities of being born into difficult situations. Both stories romanticize the individual hero, the underdog who makes a better life for himself through struggle and determination. In The Simple Gift, it is Billy who escapes a bad family situation and comes to rely upon himself for survival. In Anne Roiphe’s book, The Pursuit of Happiness, the Gruenbaum family struggles against historical forces and their struggle leads to a journey of successes and failures.
Billy (the individual) and the Gruenbaum family all struggle against outside forces to survive and pursue happiness. It is because they refuse to conform, refuse to sit passively by or get “caught in the undertow” of their situation that they are able to survive and pursue better lives.
Billy and the Gruenbaum family represent what the speaker in “Numb” wishes he could do and what the individuals in Salem should have done: change their situation, even if it means leaving the situation they are used to.
If you are referring to the film, The Pursuit of Happyness, the same thing applies. This (true) story is also about the struggle of the individual. The pursuit of happiness is the struggle itself.