The Free Movie
Bottom-up (maybe OP less so) for-fun collaborative (re)animations like this are most commonly called Multi-Animator Projects[1], at least presently in certain parts of the internet. They're found everywhere else you'd expect under different names. Some of the earliest web-originals are still on newgrounds and niconicodouga, but aren't easy to find.Another name is the pattern of "/a/ draws", "/v/ draws", "r/anime draws", etc, from 4chan. Those would be the most similar ones to OP in terms of mspaint-like quality and quantity of penises[2].[1] overview and a decent directory: https://fanlore.org/wiki/Multi_Animator_Project[2] archived results page with no personalization: https://archive.is/80U5G