I think that it comes to length of the game after all, if it was a full game with let's say 10-15 levels you would have much more time to introduce both setting and characters (and what's important for me clearly define difference between these 4) and reason obstacles they are facing, right now it felt like reading chapter in the middle of a book from a situation-action perspective. 4 characters are percieved as one game character since they perform same function and as a result situation also feels just as a game scene with a puzzle to solve not q story