It would depend upon what you consider the main conflict. There is the obvious conflict of man vs. nature, with Karana and her brother (and ultimately just Karana) left alone on a deserted island to fend off wild dogs, forage for food, build shelter, and survive illness. There is also Karana's internal conflict as she deals with loneliness and comes to love a wild dog that she tames as a companion.
The external conflict is resolved when Karana survives long enough for a boat to finally take her away to civilization. She has defied nature. The end of the novel does not resolve Karana's internal conflict, but an afterword informs readers that the woman upon whom the story is based, who was given the Christian name Juana Maria, died on the mainland a few years after leaving the island. No one was able to decipher her speech (all the rest of her tribe had died) so we don't know exactly how she felt about being "rescued."
A larger conflict, treated tangentially in the book, is the exploitation of indigenous peoples by foreign invaders. First, a ship of Russian fur hunters cheats on a deal with Karana's tribe, then they kill many of the islanders after they protest. A substitute chief paddles into the ocean in his canoe and sends back a "giant canoe," a ship filled with missionaries. They take all the members of Karana's village (except her and her brother) back to the mainland in order to convert them to the Christian faith and teach them to live in a largely white world. The resolution to this conflict in the book mirrors how such conflicts were resolved in real life at the time: by brute force and by conquest in the name of religion.