This category lists the various people that been associated with The Twilight Zone, both in reality and in fiction. The "Characters" sub-category contains the latter, while "Real People" includes people that have been involved with the franchise on the production side.
Character categories are separated by specific attributes (e.g., "Male Characters", "Female Characters") to allow for easy access and organization by subject. As this is a fictional sub-category, "Characters" may contain atypical groups like "Aliens" and "Demons" which are not generally considered to exist in reality—or at least have not had their existence proven...except in the Twilight Zone.
Conversely, the "Real People" category is generally assumed to apply to the one verified group of sentient beings: humans. This makes a "Humans" sub-category redundant and unnecessary. Instead, it is more likely to see the category divided up into various occupations or associations to the franchise.