Nazi "Book of Virtues"
At least in origin the English Royalty was not absolutist, constrained by both the Church and the ancient liberties of common law.
"Disputing over the body" is surely a common enough pastime of government, however. Let's not forget the latest and most insidious version of the Lie: persuading the people that they own themselves is perhaps the best means yet to keep them in servitude.
The statement would have been truer if you simply wrote "the foundation of modern government." Certainly, modern democracies and republics also make the same claim. "Royalty" in the sense of Christian monarchy as it had existed in Europe up through 1918 made absolutely no claim that "a person and his body" (by which I assume you mean spiritual as well as physical ownership) were the property of the state. That is not the Christian view and every monarchy in Europe from 800 AD to 1918 was overtly, unashamedly, and officially Christian, complete with the sacramental investiture of the executive.