Why does the International Dance Championship not include other kinds of dances such as Chinese classical dance, Persian dance, Indian dance, Dunhuang dance and so on?

Because, the international standard dance is a fixed concept, which contains the dance types belonging to the more popular international Latin, modern dance types, does not include the dance types you said. They are:

Modern dance department: waltz, quickstep, tango, foxtrot, Viennese waltz

Latin dance department: cha-cha, samba, rumba, bullfighting, cowboy