Remnant Population
by Elizabeth Moon
The main character, Ofelia, lives on a fictional planet colonized by Sims Bancorp company.
Ofelia hides in the woods until the others leave the planet; no efforts are made to search for her due to her lack of value to the company. She lives alone in the village until a group of the planet's natural inhabitants make contact. She teaches them her language
When the existence of the species is discovered by other humans, scientists and military personnel arrive on the planet and come into conflict with Ofelia's perspective on how to interact with them. By the end of the novel, Ofelia's experience wins out and she lives out her life on the planet, and other elderly humans are brought to the planet to serve as Nest Guardians.