I think your issue is that you’re jumping ahead a little too much. Examining the blueprints for the sample projects won’t help you. It would be like taking apart a ferrari before you’ve even learned the basics of how a combustion engine works. I think you also need to focus on one area at a time; your post touches on blueprints, the UE4 editor and 3D modelling.
It sounds like you’ve made the most progress so far in modelling, stick with that first and try to get a few textured models in your game before you think about trying something else. Once you’re happy with that, try creating a whole environment. Then start looking at incorporating gameplay.