The thing to do with Keyboard Maestro is turn OFF all the built-in macros.
Then look them over and test any that look like they'll be useful to you.
Then look at how they're built and learn from them.
Keep the rest for reference as well and move them into a disabled macro group called something like “Example Macros”.
Keyboard Maestro is a race car.
Someone who knows how to work on an old pickup truck will be able to get quite a lot of things done, but like many things there's a learning curve to more advanced usage – and you need good examples along the way.
The forum is a great place to find such things, but you don't want to throw away the homegrown stuff while it's still useful.
All the default macros, and a bunch of other macros, are available in the Macro Library within Keyboard Maestro. So there is no need to re-install to get them back, you can get any of those macros back by installing them from the Macro Library window.