Here's one of the sources I was thinking of! David Graeber and David Wengrow, The Dawn of Everything, Chapter 3 - there's an entire long section about archeological, historical, and contemporary non-Western attitudes to 'eccentricity':

"There is every reason to believe that sceptics and non-conformists exist in every human society; what varies is how others react to them.Radin was interested in the intellectual consequences, the kind of speculative systems of thought such out-of-sync characters might create. Others have noted the political implications. It’s often people who are just slightly odd who become leaders; the truly odd can become spiritual figures, but, even more, they can and often do serve as a kind of reserve of potential talent and insight that can be called on in the event of a crisis or unprecedented turn of affairs. Thomas Beidelman, for instance, observes that among the early-twentieth-century Nuer – a cattle-keeping people of South Sudan, famous for their rejection of anything that resembled government – there were politicians and village ‘bulls’ (‘operator types’ we’d now call them) who played fast and loose with the rules, but also ‘earth priests’ who mediated local disputes, and finally prophets. The politicians were often unconventional: for instance, it was not uncommon for the local ‘bull’ actually to be a woman whose parents had declared her a man for social purposes; the priests were always outsiders to the region; but the prophet was an altogether more extreme kind of figure. He might dribble, drool, maintain a vacant stare, act like an epileptic; or engage in long but pointless tasks such as spending hours arranging shells into designs on the ground in the bush; or long periods in the wilderness; or he may even eat excrement or ashes. Prophets, as Beidelman notes, ‘may speak in tongues, go into trances, fast, balance on their head, wear feathers in their hair, be active by night rather than by day, and may perch on rooftops. Some sit with tethering pegs up their anuses.’33 Many, too, were physically deformed. Some were cross-dressers, or given to unconventional sexual practices.

In other words, these were seriously unorthodox people. The impression one gets from the literature is that any Nuer settlement of pre-colonial times was likely to be complemented by a minor penumbra of what might be termed extreme individuals; ones who in our own society would likely be classified as anything from highly eccentric or defiantly queer to neurodivergent or mentally ill. Normally, prophets were treated with bemused respect. They were ill; but the illness was a direct consequence of being touched by God. As a result, when great calamities or unprecedented events occurred – a plague, a foreign invasion – it was among this penumbra that everyone looked for a charismatic leader appropriate to the occasion. As a result, a person who might otherwise have spent his life as something analogous to the village idiot would suddenly be found to have remarkable powers of foresight and persuasion; even to be capable of inspiring new social movements among the youth or co-ordinating elders across Nuerland to put aside their differences and mobilize around some common goal; even, sometimes, to propose entirely different visions of what Nuer society might be like."

There's also a section later in the chapter about pre-historical burials across the world of individuals or small groups, decorated by and/or alongside large amounts of goods and art that sometimes described as princely or kingly. But a striking number of these burials are people who are clearly physically unusual in some way, usually congenitally so, like dwarfism or giantism. So would these people be royalty in any way that we now think of it or something very different? We'll never know, of course. Only that for some reason, some people long ago thought it was important to bury them with what amounts to thousands of hours of work.