The pacing was off
It needed something to make the whole thing feel more fluid; and more like a collaboration instead of a bunch of vaguely related clips. Collaborating on a project doesn't mean getting hold of loads of 2 second clips and sticking them together, it means working with other people to create something that you couldn't have done alone. This was just a way of only having to spend an hour on the animation and being able to submit it. The sad thing is, there were some genuinely well animated segments in that, that the animator could have spent time on alone, fleshing it out into something impressive. But instead, their work will be overlooked as part of yet another, hastily assembled, "collab".
Still, as bad as I've made that sound, the whole thing would've probably worked if you'd had one song playing all the way through all the clips; maybe at half the volume of the sfx.