So, I tried to write down my spoiler thoughts and interpretation of the movie. For some reason, stuff like that is really difficult for me but I'm going to just share it
So, now to my interpretation with spoilers. In my mind, it's hinted very early that we're dealing with a god-like or something like "an old one" ala Lovecraft creature here. The first thing we see from it, is a coin with the writing "In God We Trust" on it. Now, I assume that every coin in america has that writing but still, you get my point. It would also fit to the overall message about animal cruelty or how we want to play gods and control animals for our sake. That and the way the creature can bend the laws of physics to their will, apparently. It shouldn't move the way it does and to me, it's no coincidence that the praying mantis blocked the view to the camera. I think that Jean Jacket has some influence on nature and unstable people which we'll get to right now. It's pretty obvious that the cinematographer has some issues which makes it easier for Jean Jacket to influence him.
About the shoe, I don't think it's important why it was standing, it's more as to that it was standing up so that Jupe had something to look at that's not Gordy which is something that saved him and gave him a false security. Thinking he could tame or trust any animal which then led to the tragedy of the Lasso experience. Now to the end. To me, that proves even more that it's an angelic or god like creature, just by looking at it's design and I also think that OJ died and that the ending shot is what the character would've loved to see cause we do hear a horse screaming the moment Em rides away on the bike and the soundtrack name suggests as well that OJ died there.