Hey! Thanks for the feedback and for playing!
Regarding the things you were grabbing, they were items that the player could consume during the levels to either gain health, increase speed, fill up the secondary atk bar (if not full already), and to become invincible for some time. Initially I did debate whether the player should consume or drop them in the hole in order to consume them. I decided that you would just need to grab them because, with enemies on screen it would probably become too difficult to manage everything.
By itself as you mentioned, the mechanic does not make much sense.
Regarding the goal of the game, drag and drop enemies into the hole and eventually the stage boss. But due to time constraints I was not able to finish this :/
Thanks again for playing! :)