Say you find an external class library that you like, and will want to use over and over.
I know you can add the jar files to each new project manually, but that is a lot of repetition.
Can you add them to Eclipse so that they will be available to any new project automatically, so you only have to type an import statement?
The idea behind an Eclipse project is that it is something big, which you will spend several weeks or months working on. So you only have to load external jars rarely. And they are often different jars.
Make all your learning applications part of one large project, then you won’t have to repeat the importing.
I shall move this discussion to the IDEs forum, where you might get more comments.
Back when I did stuff like that, I made a dummy project named "libs", put all the JARs in a directory in the libs project, then defined a symbolic path to them so that the consuming projects wouldn't have to code absolute paths.
These days I use Maven and the jars all come from the Maven cache automatically.
An IDE is no substitute for an Intelligent Developer.