That's not the point of the novel or of any of Hesse's works, really. Try to finish the novel. If you still don't understand it, look up an anaylsis of the work.

Write your own story that has the ending you want

Unless the author publishes a detailed paper on what they wanted to communicate in their work, you never really "get" a book.

You only get your subjective perception of the book. Now, I'm not saying that the author can't communicate a message to the reader, but not all authors try to do that.

Some authors just want to write a a bunch of characters and events and stories and don't really care if the reader understands the point or meaning. Some works of art don't have a true meaning.

Just because a book doesn't have an understandable meaning, however, doesn't mean that it's bad or unenjoyable. Goodness and enjoyability are just subjective to the reader.

that's literally anything. "Is this book fun?" "Yeah, if you're into it"

literally how likes and dislikes work. Entirely subjective