Speak with Impa who can be found here and she'll give you some backstory about the Goddess Hylia and the evil Demise. (zeldadungeon.net)
The recent reveal of Impa as a playable character is big news for the game, but it leaves me wondering who else could be fighting in this epic battle for Hyrule? (thekoalition.com)
Heck, even reactions from Impa, Purah and the town elders differ based on stuff like if you've freed the Divine Beasts or gotten the Master Sword! (gamingreinvented.com)