If an eight year old read Genesis 1, he or she would understand that the world was created in 6 days; or at least would agree that the text said that.
A typical Christian adult, one who read books, would hum and har, and say maybe this, or maybe that, or 'it could be read that way' or 'you have to understand the genre', and so on.
So, what happened between 8 and 28?