I always found it annoying that you can’t use all the vanilla animations. I know that Nelson made it that way so you can’t steal the animations, but my idea is that if you copy an items folder and do the process so it shows your custom item, it has the animation from the original item. The file containing all the vanilla animations could be called animation set. Within that folder there will be folders that say Animation Set(X). It could be organised by numbers through 1-100. If you have custom animations then you will have bundle the animations up in a .unitypackage, and set up a folder for them. There should be a .txt folder or notepad++ file in it with the animation names. You can even have vanilla animations and custom animation in. Here are some examples of how it could look.
Epic games launcher
We have a Fortnite boi.
All item animation files are already public.
Also you should update your Unity imo. Any version of Unity 5.5.x will work, but the current version Unturned uses (until it upgrades to Unity 2017.4.3f1) is Unity 5.5.3f1. Just a little nitpick since the thread’s purpose is already kinda dead.