Recently I stumbled on the seeder plugin from studio espresso.
It is a great plugin to generate dummy content in Craft CMS!
It is not available in the Craft CMS plugin store, so you have to install it manually (and enable in the cp):
composer require studioespresso/craft-seeder
You can then generate dummy content with:
./craft seeder/generate/entries --section=sampleContent --count= 15