It’s the Alpha Male thing.
The whole march towards civilization has been REPRESSION of those murderous impulses. The Strongman of the tribe got there by, well, murdering his rivals, with the implicit threat of again murdering anyone who challenges him.
The Noble Savage is just another of those myths that the Beta Males dream up to try to shame the Alpha Male into behaving.
Why would shame exist unless there was a Reference? That humanity knew about in spite of every attempt to suppress it from thought and mention?
There was Someone who was not only Alpha, but he also was Omega.
Alpha males in civilization exist to go to war... Kill the enemies or die trying. Beta males are not in direct harm’s way so they are busy with arts, science and business.