The important concepts in this book include the difference between slave morality and master morality.
Nietzsche tries to help the reader understand that there are no absolutes and that everything can be understood differently from a different point of view.
He sees the greatest danger as the mindless, instinctive herd, and warns strongly against it, including especially the flawed and oxymoronic concept of the "common good".
Since the rise of the Jacobins, more people have been murdered, starved to death or enslaved for the "common good" than for any other excuse.