Well then it sounds you are not really looking for prototyping material but closer to final which most likely means you need to buy or make em yourself as there are hundreds of ways character can walk, die or do melee/ranged attacks.
Precisely. Having to mess with setting up the various animation states to show the right actions is something you’d do a good bit further on than prototyping anyway. For prototyping, the included Standard Assets should more than suffice. Who’s to say in a prototype that a player’s attack can’t be represented solely by a flash of red light, or a console message?
Spending too much time polishing a prototype is a great way to never finish things (speaking from experience!).
You can get mocap animations from animators really cheap. Check the commercial section. There’s also plenty of free stuff on the asset store, both characters and animations. Ostwind is probably absolutely correct here though.