Although this may seem harsh, it is not really. Not on you as a team. It may be harsh on the Epic Games judges, but not on you. But my honest opinion is that I do not agree with your game being the winning entry. The art is well done, and that is all; apart from the art, you have little more than a third-person character running and jumping and some basic enemies that does nothing but chase the player. Since your game won, I am now of the strong opinion that the judges gives much more credit to art, than to anything else. And to be honest, in a game jam, which is at least as much about software development as it is about art, I think this is not appropriate.
Note though, that you are clearly very good artists, and I commend you for that. It is a skill that I envy!
I do however think that given that your game is little more than a third-person character running and jumping, and even for the running part you used Dynamic Locomotion and not something you wrote yourself, that this is not a technical accomplishment at all. An artistic one sure; but this game screams 'art' where I think, in a game jam winning entry, the entry should scream 'technical accomplishment' or 'gameplay' first and art a close second, close but still second.
Anyway, I just wanted to share my view on this. A win is still a win, and I congratulate you on winning! I am sorry if it feels like I am saying 'you did not deserve to win', which, to be honest, I guess is what I am saying :). But I am not saying it against you. My entry to the jam was such a waste and junk, I did not deserve to win either, not nearly as much as you did, it was junk. Your game is orders of magnitude better than mine. So, I guess all I am trying to say is that I am disappointed in Epic for being blinded by the ability of 5 artists to push out large amounts of good looking art, and them losing sight of what a game jam is all about.
By the way, I think that your game would have been a worthy winner with just little effort. Interesting dynamic puzzles, some basic mechanics, just a couple of things to demonstrate that you can develop more interesting gameplay elements, and I would feel you deserved to win. I just really struggle to consolidate your winning against many other entries, and good ones, when your game is little more than an empty dead world with nice art.
If you are going to develop this game further, which I hope you do, I recommend you focus on story, and gameplay (maybe puzzles or a more dynamic world with crumbling cliffs or things like that). And as beautiful as it is, the world seems very static, I recommend you make it alive.
My rant is over now. Let me end with saying this is still a great artistic accomplishment in the little time you had. So good work, very good, despite my belief that you should not have won. And you did so, congratulations! I hope you continue working on this game and making it really amazing, I can see that being possible!