Lobengula had 80,000 spearmen and 20,000 riflemen, armed with nine pound Martini-Henrys which were modern arms at that time. However, poor training meant that these were not effective weapons.

Hardware is tiny part of technology. This wasn't an army with modern technology - just a mob which got its hands on hardware, without any of the know-how and training necessary to use it properly. And in any case rifles were already ancient technology by then - the battle was won with Maxim machine guns like most battles of that time.

Such number are not atypical. See battles of Carrhae, Legnica, Poitiers, Německý Brod and many others - all against modern enemy armies, not some Neolithic mobs which got its hands on some hardware it didn't know how to use. It was very typical about warfare that losing side got massacred while fleeing, so 10:1 casualty ratios were the norm, and 100:1 not unheard of.

As for Hitler, organization skills require a lot of intelligence.

"Hitler rose to a place of prominence in the early years of the party (1919 - 1923) largely as a result of his considerable skills in oratory, organization and promotion."

Yes- notice how rationality and intelligence are not on that list.

Intelligence should be, or at least it should be acknowledged that high generalised intelligence allowed success in the diverse combination of skills mentioned.

They had twenty thousand people who were armed with rifles, which means that, even if they had a backwards culture, their technology was very far from Neolithic.

Even if you disregard the rifles, the Ndebele were not a neolithic culture, since they worked iron.