General Synonyms:
* Native
* Aboriginal
* Autochthonous
* Innate
* Natural
* Original
* Endemic
More Specific Synonyms:
* For people: Native people, First Nations, First Peoples, tribal, ancestral
* For plants and animals: Native species, endemic species, naturalized, wild
Other Related Words:
* Ancestral: relating to or inherited from ancestors
* Traditional: based on or following old customs
* Original: existing from the beginning
* Inherited: received from an ancestor
The best synonym to use will depend on the specific context and the intended meaning.