The original question had to be edited down. I would say that the conflict in the story rests in the choices that individuals make. The level of choice that an individual makes is where there is conflict. On one hand, the idea of remaining in Omelas knowing at what cost one's happiness is derived is part of this choice. On the other side of the equation exists what happens when individuals fully understand the implications of their own happiness in terms of needing to leave, to become "the ones who walk away" from Omelas. It is here where I think that there is a clear conflict present. One side of the dilemma displays individuals who find it acceptable to have their happiness come at the cost of this child. The other end are the individuals who either cannot live with this situation or find themselves needing to assuage their own guilt by leaving Omelas. It is this particular choice that Le Guin forces upon the reader, who must wrestle with what they would do and how they function in their own social setting with paralells to the situation offered in the life of Omelas.