Very excited to see more, the system you are going for gives me hope we can see a lot more cultures included that wouldn't make it otherwise with civilization style mechanics. As a fan of mesoamerican history, and seeing the Olmecs are in (I think they were mentioned in an article?)* , can't wait to see if you can choose Toltecs, Zapotecs, Purepechan, etc.
The announcement so far has indicated 6 Eras with 10 "Factions" per Era. Covering the whole world in 10 "Civs" makes having 2 Meso-American Civs in the same Era a little problematical, given that you also have Europe, Africa, Middle East, Central, Southeast, Southwest, and Northeastern Asia, North and South America, and 'niches' like Western versus Eastern Europe, Scandinavia, Mediterranean, Balkans, etc.
On the other hand, since China has been indicated as having Civs in several Eras, Meso-America could get, say, Toltecs early on followed by one or more of their 'successor' states like Aztecs, Mayans, or even 'modern' Mexico or one of the Central American Post-Colonial states. Same thing for, say, France, which could start out in an early Era as Gaulic Celts, then have a chance to change into Merovingians, then some kind of Royal France, then 'Modern' France (given that between 1785 and 1985 they had Royal, Dictatorial, Imperial, Royal again, Republican, 'DeGaulle' Republican, and the modern French Republican With Lots Of Foreign Entanglements versions of governments/societies, there's lots of room for Multiple Industrial and Later Era French Factions!)
What is exciting is that
Humankind, by freeing itself from the straitjacket of Named Famous/Infamous Leaders, opens up a wide range of potential Factions in every Era. Olmecs are a good example: Civ could never 'do' Olmecs, because we don't know their language, leaders, or even any City Names (be interesting to see how
Humankind handles that).
On the other hand, all the previous Amplitude
Endless games had "Heroes" - special leaders/actors that influenced the game. Haven't heard Word One about such a mechanic in
Humankind, but it would seem like a natural way to Split The Difference between Civ's Leaders and Great People: they might be temporary (say, limited to the Era in which they appear) but it would be a way of getting Individuals that have influenced History and Civ Development into the game in a different way than Civ does and with a 'nod' to their previous games. That would also be more flexible in that "Semi-Leaders" like Joan of Arc, Benjamin Franklin, Cleisthenes of Athens, or Aleksandr Nevskii could be included, potentially enlarging the "pool" of Great Named People almost infinitely.