I think there were a lot more male citizens than that. 6000 was what they could fit in the agora. First they used public slaves to round up people to make quorum; later they paid for Assembly attendance, and the slaves made sure only the first 6000 people got in.

Fantasies with government but no monarchy at all: I don’t know of any.
Fantasies with non-monarchy governments: Hobbit and LotR for startes; Master of Lake-Town and Mayor of the Shire (okay, of Michel Delving) were elected.
Hmm, Lud-in-the-Mist? Elected mayor as the only human government I think, maybe elfland monarchy. Small scale, though.

The Liveship Trader books feature foreign despotism, and a native oligarchy that undergoes democratic rebellion.

David D. Friedman wrote a ‘fantasy’ with Icelandic anarchy vs. an intruding empire. Fantasy in quotes since I can’t recall any supernatural elements, more like secondary world history.

Webcomics: Errant Story didn’t have any monarchies. Vague council in magical pseudo-Japan; frontier libertarian anarchy; pseudo-Catholic theocracy; vague elven council; northern city-states.

Googling:
“R.A. Salvatore’s Icewind Dale Trilogy depicts a group of ten towns that are governed by a democratic council.”

“China Mieville’s New Crobuzon (in Perdido Street Station and other books) is a city-state and a republic, though a very corrupt one.” I don’t remember if the leader was strong enough to count as a monarch.

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“For everyone to be able to vote you not only need some form of instant long-distance communication to coordinate elections, you also need to be able to show everyone who they can vote for and if you have a very large state it’s not very feasible for candidates to travel all over in a limited amount of time”

These sorts of arguments imply that the 1787 USA couldn’t have existed. Colonial US stretched over a long distance, and soon spread to inland areas like Kentucky. And that’s with presidential elections and two-year House elections, never mind simply having a longer term Parliament of local reps.

Democracy doesn’t have to have modern forms. You could have the European proto-democracies, of a strong king ameliorated by a nascent House of Commons or Estates-General — how many fantasies even have that? And of course the Athenian and Roman models are pretty different from modern times, or each other, and could inspire a lot of permutations. (They were arguably too democratic — too tied to direct democracy within the city — to extend easily to their empires, unlike US representative democracy. Can you imagine ways in which they could have evolved their own distinctive ways of sharing power with their colonies and empire?)

The reader in me says that monarchies offer a convenient way to both isolate and contextualize a main character – the king in waiting, the spare heir, the disgruntled uncle, the hidden king. It directs our focus to a specific individual while simultaneously placing that individual in context vis-a-vis his or her entire society. It also offers a compelling reason to care about what happens to this character – the fate of a country is in his (or her) hands, and as modern residents of democracies, that matters to us.

The political scientist in me says that monarchies are, after tribal/clan systems, the next obvious means of social aggregation. Tribal systems usually have a sense of locality – a focus on a very local geographic area – that monarchies transcend, usually because of technological improvements (roads, horses, carts) as the society evolves. (In fact, central monarchies in modern-esque states evolved as technology rendered individual clan leaders and then barons/dukes unable to defend themselves successfully.) Monarchies are personalist systems, where power is rooted in a single individual and often held by force of — whatever makes one ‘powerful’ in that particular context, which differs over time and space (even among premodern European systems). In short, they provide a lot of room for variation within a single easily-understood framework. When one says “King Witgoknoph”, that immediately brings to mind not only a person but an entire system of ordering social relations. No other system, including empires and democracies, carries that full system with it. So using monarchies is a shortcut of sorts for the author on world-building as well.

As for slavery, you seem to happily ignore the massive modern slave trade that goes on today. Your clothes and shoes, your electronic items on which you type your response and so on, have quite probably arrived at your house via a slave.

What is more puzzling is how much contemporary fantasy glamorizes these shallow egomaniacs and their dim-witted children. George R. R. Martin at least sneaks a few more realistic portrayals into his series. But science fiction and the techno-thriller (up until the latest wave of dystopian novels) have often cast presidents and prime ministers (and even some corporate tycoons) as wise and humane authority figures, when for the most part they are just as repulsive as the monarchs and tribal strongmen that preceded them. Maybe, since we can’t seem to solve the problem, we’ve decided to candy-coat it so it doesn’t seem quite so bad (as long as we are not the ones being given the wonders of peace through drone bombing).

(*) significantly more often than not

BTW – the ending of the post seems abrupt, did something get chopped?