Reading response

The book Island of the blue dolphins by Scott o’ Dell is a historical fiction book about a Native American girl who has been left on an island alone waiting for someone to come and save her. What details in the book are real and researched by the author? What details did the author make up and imagine? How can you tell? This book is based on a true story so their has to be many parts that are the true story that the author researched and some parts he had to make up, like the dialogue.
      For an example one part in the book when the main character screams dog constantly. I know that the author had to make that up because the main character was alone how would anyone witness what the main character said ? So the main character probably put that in to support a part in the book.
      On page 41 the main character cries “Where is my brother?” I know the author made this up for the book because this book was taken place in the 1850s. How would Scott o’ dell know how the main character spoke exactly. Also even if he had know how Native Americans spoke in the 1850s spoke he would really know how the main character spoke. Cause she can speak differently then the other Natives.
      Lastly I know that the author made the dialogue because where would he get the information from? If he got it from a person who had a relative that was on the island how would they remember what they would say. Unless people who were there had what their acquaintances
     Wrote down what others had said. Which I doubt happened because they wouldn’t know that what they were saying right that moment was going to be history or in a book.
      Therefore the author made up the dialogue because 1. It wouldn’t be accurate. 2. It would be hard to get information about what the characters say. And 3. How the character talked