Most of the 3d assets in my game are done by others and published on the Unreal Engine Marketplace. I use blender to modify them most of the time to make them either useable or better fitting into my scenes. I started creating my game 2 years ago with zero knowledge of anything development related.
All the logic and game mechanics in my game are done with Blueprints. Blueprints are a flowchart based programming language within Unreal Engine 4 based on c++. You can do alot of things with them and they are easy to learn. Later the engine can translate Blueprints into c++ or just simulate smaller ones on runtime.
Creating a game is very time consuming, especially when you work alone, and can be very frustrating. Beginning with engine crashes, assets which will shoot your fps to the moon and ending with corrupted project files, which will let you start all over again. However you will learn from most things, you will start to monitor performance while building your level, dig into unreal documentation and backup everything daily and in the end you will hopefully have a great product you can be proud of!