Ok, so I think it's great that someone made this. I think people who are just starting out will find some good value in some of these templates.
I take issue with the fact that someone made this though because I think it flies in the face of actually digging into the product and learning for yourself. For so long designers had super cumbersome tools to figure out how to get the animations out of their heads...most just avoided doing them because the learning curve was so steep.
Now with Principle and Flinto we are able to capture those fluttering thoughts of "What if we..." and they can now manipulate it with very little loss of effort and cost. It would be better to have a showcase with how someone did something rather than "Just use this template so you never have to learn yourself".
Maybe I am in the minority. I can see how if you are just starting out that you may want this but if you are just starting as a designer, you shouldn't be focusing on the animation first, there are tons of other basic fundamentals you should learn first. Maybe I am being an asshole for saying it but these kinds of sites IMHO degrade a designer to just a copy paster.
Great resource to get started with Principle. The http://sketchapp.tv/ video walkthroughs are great for learning too.