Worldling as a noun is a mundane person, preoccupied with worldly matters rather then spiritual affairs while Earthling as a noun is an inhabitant of the planet earth (generally in science fiction aliens who use the term earthling look down on the people of earth.)
Part of speech: noun
Definition: a mundane person, preoccupied with worldly matters rather then spiritual affairs
Part of speech: noun
Definition: An inhabitant of the planet Earth (Generally in science fiction aliens who use the term Earthling look down on the people of earth.)
We hope you now know whether to use Worldling or Earthling in your sentence.