Yeah, you can't attack without using the first essence piles from the tutorial to buy the "Bite" or "Claw" abilities. A few more tips to ease players in surely would have helped!
Without an attack, the best bet is to just explore and avoid enemies since they will give up after a while and sometimes fight each other when the player isn't in range, creating more remains to feed on. There are also various objects scattered around that you can consume for essence.
I appreciate you taking the time to play and give feedback, and I hope next time I can give players a better experience! :D