Aleuts vs. Islanders
According to the islanders, the Aleuts are people who speak a strange language and can't be trusted. They kill the otters and have a history of doing damage to the Island of the Blue Dolphins (and, we're guessing, other islands too).
According to the Aleuts, the islanders are simple people who can be easily cheated or bribed with shiny beads. They think it is better to kill the islanders than risk losing any valuable cargo or goods to them.
Are these assumptions proven true in the novel? Even though these are the prejudices that each culture holds, the novel wants us to question them. The book wants us to learn to understand cultures instead of judging them before we know anything about them.
Are you animal, vegetable, or mineral? And why does it matter?
Well, at the beginning of the novel your species determines your fate on the island: otters are hunted for their pelts, and then humans trade the pelts for beads.
By the end of the novel, however, Karana comes to see animals, vegetables, and minerals in a whole new light. She thinks, "Animals and birds are like people, too, though they do not talk the same or do the same things. Without them the earth would be an unhappy place" (24.18).