What is the significance of the opening scene in The Poisonwood Bible? What does it mean, and why does Kingsolver choose it to be the opening?

In the opening scene to The Poisonwood
Bible, Orleanna Price begins the narrative by speaking to her dead daughter. 
However, in the first few pages, the narrative appears to be more the author-as-narrator
addressing the reader directly.  The first line of the novel reads:  "Imagine a ruin so
strange it must never have happened."  This direct address to the reading audience
posits the reader within the setting of the Congo as the characters will experience it. 
The land and its people are mysterious and strange to the Prices and a tragedy will
befall them that is unimaginable to them when they begin their journey.  The narrative
continues to tell the reader that he/she will have to make his/her own judgements on the
actions and decisions of the woman (Orleanna) and her daughters suggesting that the
novel will be told from either objective or various viewpoints (the latter is the case
as the reader encounters shifting first-person narrators).  After Orleanna's voice
becomes more apparent, she reveals that her daughter (unnamed) is dead and asks that her
ghost quit haunting her.  The suspense of the unknown propels the reader into the
novel.