>>531155996
You're right, the core themes aren't abandoned, but it uses certain tools to explain that it abandons later.
It's like many of the names used in the game. They're nice details and sound cool, but they have little relevance after a while. Abydos is and has many Egyptian themes but the story doesn't have a theme that really uses those well. It could be any other mythology that would fit into the story in a reasonable way.