Everything that has some kind of interaction or that needs some kind of logic will be a blueprint. A light with a switch, a simple moving platform etc. pp. will all be blueprints. And that’s a good thing.
I don’t know whether you are coming from a programming background or not, but the blueprints are also called class blueprints (level blueprint being the exception). A class is a kind of template of which you can instantiate objects. Imagine your coin blueprint in your content browser. You can create infinite instances (i.e. actual coins in your world) of it by just pulling it into your world. And that’s great. Just imagine if you had to copy and paste the coin logic again and again for each coin you want to create. And there’s more. Class blueprints are independent from levels and projects, meaning you can easily re-use them in other places. And that’s just the tip of the iceberg of the capabilities of blueprints.
Learning UE4 is a combination of things. Watching the official tutorial videos, reading the doc, reading / watching community tutorials, learning by doing, helping others with their problems. Or at least taking a look at the forum and what people post. Screenshots of blueprints, ideas etc. You can really learn a lot from these sources.