You can ride Boars, but you need to do a quick side quest at some point, but tbh the world isn't that big so you can easily travel without mount.

And yea, there will be more locations, more characters, more NPC's. But for like first 1-2 hrs the only people u basically know is Popola/Devola and ur sis. This is the game that gets better and better over time. It starts from killing sheeps, but you will see where it actually leads. And there will be a lot of bosses and interesting enemies. I think you will like the next ep . It will move the story to the next point. And that point isn't killing sheeps lmao I can't wait when u finally get to other villages and start meeting other characters, shit is gonna be crazy at some point