I want to create a 3D World.

Let me start with this, I have very little experience in coding or programming in general. I am interested in creating a 3D game in my free time, learning by watching tutorials, etc. I know programming is difficult to learn, and incredibly time consuming.
What I would like to know, is some suggestions on what tools to use to start building a world in a medieval setting that will be fairly simple to get into. I feel like the world itself is what I am most interested in creating.
Additionally, are there any premade AI? As I said, pretty new to the programming and Unity scene, so whatever I can get to make things start smoother would be nice. I would ideally be able to create a small section of a forest or village and be able to move my character around in it as soon as possible. Any suggestions would be greatly appreciated. Thanks!

Blender for the modeling. GIMP or Photoshop for the textures. There is a ton of AI on the Asset Store, as well as more models and textures and skyboxes. Just make sure you look at the license.