But...there's very little that's Sumerian about the design.
What is there is Sumerian. It's just extremely simple because it's baby's first civ.
A more Sumerian design to me would be bonus faith from Monuments (priest-kings and all that)
Spammable ziggurats are more resonant and fun(!).
bonus food from farms with fresh water (early irrigation)
Ziggurats get a river adjacency bonus.
and a focus on small empires with big cities (like the Maya)
You can make big cities by spamming ziggurats!
Ziggurats are Sumerian, of course, but the design looks more Mesoamerican to me--and a unique improvement was the wrong choice for them. They should have been a Shrine replacement that generates culture. That leaves the War Cart, which may or may not have been actually used in combat but despite that is probably the most Sumerian thing about the civ. So to me the civ still looks 100% Epic of Gilgamesh.
I would have supported the shrine replacement. But the point is that Sumeria, as a base game civ, leaned hard into being
as simple as possible. You spam ziggurats to build your cities. You spam warcarts to take others' cities. You make friends with everyone. It's a consequence of the developers deciding that Sumeria was important enough to include in the base game. where most, if not all of the civs, had much simpler designs and Sumeria happened to be a strong candidate for one of the simplest introductory designs. If Sumeria had been included as DLC or expansion content and not been shoehorned into tutorial duties, then we could be having the conversation of how complicated it could/should have been. But for a franchise that grows increasingly more complicated that felt compelled to make itself more accessible to new players,
somebody had to take one for the team. And that was Sumeria.
Uh, what about Phoenicia and Persia looks particularly unique to their respective leaders? Phoenicia is all about trade and coastal colonization--just like historical Phoenicia. Cyrus' portrayal isn't even particularly historical, but the Pairidaeza and Satrapy bonuses are things I'd more associate with his successors like Darius and Xerxes.
Dido serves as a folk hero personification in the same way Gilgamesh and Kupe do. They aren't really mechanical choices so much as choosing legendary names as blank slates to represent civs without strong options for leaders. Hannibal would feel weird leading "Phoenicia." None of the historical Maori leaders of note actually led the Maori people as a whole. And none of the Sumerian kings are common knowledge.
Cyrus as representing the height of the Achaemenids is somewhat a personification of Iranian nationalism in the same vein as Tamar. Again somewhat of a blank slate to broadly represent Iranian heritage.
And yeah Alexander is a folk hero in Macedonia, but my point is that Macedonia, unlike Persia, or Georgia, or Phoenicia, is borderline irrelevant in a game that already has Greece as represented by the Delian and Pelopponesian Leagues. The Hellenic league is more of the same, and Macedonia's greatest accomplishment, the conquest of Persia, began to fall apart as soon as Alexander died. As far as representation goes, Greece and Persia cover much longer legacies that obviate the need for Macedon in VI. And yet Macedon was still included,
solely for the sake of Alexander. If a figure as uniquely narcissistic as Alexander hadn't gained such a cult following in the west, Macedon would have been passed over altogether, relegated to "not needed" alongside the Seljuks, Seleucids, Hittites, Palmyrenes, Medians, Lydians, etc. etc. I still hold that Macedon is the only civ in the game that was included for the sake of its leader, not for its own sake.
Colombia comes close, but at least represents a culture and legacy common to several Spanish colonies that were not yet represented in the game, so even though Gran Colombia broke up shortly after Bolivar's death and he has an entire country named after him, Gran Colombia at least serves additional functions outside of being an excuse to put Bolivar in the game. And at this point I can't think of any other leaders which would be an Alexander outside of maybe Maria Teresa. Even other short-lived cults of personality like Zenobia or Timur would at least fill out unrepresented regions on the map.
