Earth is not the story. It is the cover.
Book 1 begins with Henrik's ordinary life so the scale of Andromeda has somewhere human to land. The hook is not only that a galaxy was stolen. It is that Henrik belongs to that stolen history before he understands what it will cost him.
The opening should give you three answers fast: who Henrik is before command, why Andromeda needs him, and why refusing the call will not keep him safe.