Yes, divine right of kings is inconsistent with nationalism. Sovereignty either comes from the people or it does not. Are we going to equate nationalism with "people who have a vague sense of being similar in some way"? That's identity in general. Are we going to consider tribes to be nations now? Or all states for that matter?
National identity does predate nationalism, but by decades, not millennia. That identity presupposed interaction between different parts of the nation, which didn't take place until the urbanization associated with the industrial revolution. It requires people to know national myths, which could only happen on a mass level after the printing press and a certain level of literacy. It requires people to identity as members of a certain nation (which is why ancient Greece wasn't a nation; people might have had some general sense of being Greek, but they identified with their city-state), which did not happen until the 19th century. Someone could literally be English one day and French the next (based on conquest) without even understanding what happened. The peasants frequently didn't even speak the language of their lords.
Meanwhile, nobles identified with their House. They might have had some residual loyalty to their king. But that's a loyalty based on dynastic ties, not nationalism.
What made that revolt different to the ones carried out by various tribes of barbarians subjugated by the Romans? No one likes being oppressed.