Terricola term that identifies the inhabitants of planet Earth, is commonly used in science fiction to contrast organisms and characters born from Earth, whose ethnicity or nationality originated on Earth with extraterrestrials. Similar terms are Terran and Gaian.
Historically, the term "earthly" referred to a mortal inhabitant of Earth as opposed to spiritual or divine entities. In early modern English, the word was used with the intention of contrasting "earth" with " heaven, " and thus presenting man as an inhabitant of the sublunar realm, as opposed to celestial creatures or deities. The derivation of the noun earth by the suffix -ling is already seen in Old English eyrþling, in the sense of "farmer". The sense of "inhabitant of the earth" is first attested in 1593. Its use in science fiction dates to 1949, on the red planet by Robert A. Heinlein.
The term earthly would be somewhat redundant if some of us said that we are all and that it is part of our essence: as a known life within the solar system, earthlings can only be those who were born and inhabit planet Earth. That is why the word is only used by aliens in those fictional stories in which there is a possible contact or invasion of beings from another world to ours. Normally, alien stories are generally attempts to invade or dominate strangers to the inhabitants of Earth, so the meaning given to this term is usually negative or derogatory seen and considering that aliens are estimated higher.
When we talk about earth we are talking about a person who lives on planet Earth. Another term similar to that of terrestrial, which also refers to our planet. However, this last concept is a bit more limited since in some cases it is used to distinguish all animals and plants that live in terrestrial space as opposed to those that live in aquatic environments or in the air.
