In "The Country of the Blind," Nuñez might represent a number of people and personality types in the real world, given that Nuñez's own personality (and his relationship with the villagers) can be framed in a multiplicity of different ways across the course of the story. The frame through which you perceive Nuñez will then shape which real-world parallel he would represent.
For example, at the start of the story, when Nuñez falls into the valley, he displays an arrogance about himself, assuming that his possession of sight makes him superior to the blind villagers. Of course, the story's irony is that, to the blind villagers, his possession of sight marks Nuñez as insane, and they thus hold themselves superior to him in much the same way he does to them. In this sense, there are already two distinct frames through which you could view Nuñez: you can view him as the arrogant outsider convinced of his own superiority, looking down on the people that surround him, or you can perceive him as someone isolated within a radically different culture, with neither Nuñez nor the villagers able to bridge the gap between them.
Either of these options presents a distinct facet of his characterization, and depending on which of these you might focus on, a very different real-world parallel would result.