Will it be restricted to "civilized" races, or is any race a possibility, such as goblins and (not sure if they're in) kobolds? Or is this not decided yet?

Sorry for a late reply. Corona got in the way of development and we haven't been paying enough attention to our media.

To answer your question, here is the list of currently planned (playable) races:

https://sote.miraheze.org/wiki/Races

In general, we won't be limiting you to "civilized" peoples only. You will be able to play as (organized) tribes of hunter gatherers or nomads.