Cool concept, but I think it needs a little more gameplay wise. Add recovery or start up time to the dashes. Add a few more attacks for each enemy. Also I'm not a huge fan of the auto aim system. I prefer crosshairs even if they aren't completely accurate as long as they are consistent (starfox 64 as an example). I wouldn't change anything about the platforming, seems like a solid formula so far.
The demo also feels very linear with little exploration. Leave town, do level, talk to guy, get shovel, go through hole, etc. I don't have to learn anything about the world to be successful, I just have to get my next objective and continue. But I think the shovel part was on the right track. Maybe have the player decide where to dig rather than automatically letting them progress. Add a few secrets that you can dig for and you have a more interesting and interactive world.
TLDR; The two most important things to focus on with a small dev team would be combat and level design. Other improvements can come later if there is time.
That's just me though. That's what I want to see more of in this game.