David Y. answered 07/02/19
English (Language Arts) reading/writing/editing specialist.
William,
I think you answered your own question as to why Sounder is the only character with a proper name.
The book flowed so smoothly the first couple of times you read it that that fact was barely noticeable. The answer likely lies in the fact that the book is about Sounder and the story line is viewed through his eyes. It's a story that is somewhat anthropomorphic in that Sounder takes on human characteristics and feelings.