I love that little fox and crow model! They're stylized in a very cute, simple sort of way.
However I don't think this actually meets the limitation: you've at the very least got both pyramids and cubes, and it looks like there's extrusion on the crow and the fox (it's hard to confirm without a download link for the model).
Viewing post in Biggie Cheese jam comments
Moving vertices to overlap to do things like make a cube look like a pyramid is unfortunately also against the theme: "You may move vertices, but do not make vertices of the same mesh overlap positions."
I don't know if it will actually let you add a new file or not during the voting period but technically you should have the model available anyways as per the jam rules: "Please submit an animated Gif spin of your model, the model txt, and if you have it, the texture png."
At any rate your model is very cute it just goes a bit against the spirit of the limitation.