We only have MiB (Smokies) explanation for the names so far (he may be lying). They are apparently a long list (100's?) of people that Jacob considered for becoming a candidate.
Their names may have been crossed off as they each failed, or perhaps were stopped, or simply were not the right choice. It appears the only names left are the losties.
Its also not clear if Jacob somehow designated who he had to choose from in writing the names, or if Jacob simply found out some people were 'special' and so added their name to the cave.