There is such lore, but I've forgotten most of the details. The lore accounts for time passing through Ages, and I believe that Launch will happen in the Fourth Age. The First Age was before there were any Children of Mann (who will be the characters in the game).
I don't think detailed knowledge of the lore will be necessary for role-play. You can probably do fine using the religion and tribe characterizations. Some kingdoms have been actively role-playing in their own discord channels for several years already, albeit at some risk that their RP may not exactly match the religious and tribal context that they end up with.