[quote=@Willy Vereb]
Are we limited to only humans as our dominant species?
[/quote]
Keeping it limited to human here today, basically. For fantasy's sake I may permit a cameo of one or two elves as free agents from regions outside of the current narrative area, elves and shit. Dwarves may as well be a minority if we apply the Tolkein logic of them living in underground cities, in which case they either drowned early or somehow managed to seal themselves off and are forever lost. Either way, less a political factor than adventuring elves or the like.

[quote=@Willy Vereb]
 What tech level of medieval we should think about? How would magic and fantastic elements factor into this?
[/quote]

Late middle ages. About 15th century equivalence.

[quote=@Willy Vereb]
How would magic and fantastic elements factor into this?
[/quote]

I'd rather not literally involve magic. I'll permit it in a sort of esoteric, mysticism sort of way though. No magic missile or enchantments really. But a veneer of magic can be applied.