Wow! Lots of beautiful content. Where do they come from? Are they from multiple artists or did you make them all? 

Unfortunately appears to be (likely unauthorized) uploads of content from various sources. Compare e.g. 

http://www.unity3dasset.com/rpg-medieval-kingdom-kit-v1-2-unity-rpg-assets/

with 

https://assetstore.unity.com/packages/3d/environments/fantasy/rpg-mediev...

or 

http://www.unity3dasset.com/polygon-western-frontier-pack-unity-low-poly/

with

https://assetstore.unity.com/packages/3d/environments/historic/polygon-w...

At the bottom of the page

NOTE：This pack is for learning game development only, Commercial use please support author!

The most charitable interpretation is that these are released for free under an alternate educational/personal use only license. Personally, I doubt it.