Have you looked at The Life of George Washington (school edition) by Chief Justice John Marshall? I believe it is the earliet biography of him known.
I don’t know how “narrative” it is, but it is one I will be using for my children when they get to be about your child’s age. It is an author-abridged version of a five-volume work that was done within eight years of Washington’s death and by someone who knew hi personally.
I should have prefaced that with “I haven’t seen it yet…” and I”m not sure what age “school edition” means. It was made prior to the War Between the States. HOwever, I’m looking forward to using it.