I'm struggling to see the amazing advancement in all this. It's really just that a rocket landed, right?
Nope. It's not "just a rocket that landed." It's the implications of re-usability. It's the cost reduction. It's much larger payloads. It's a technology demonstrator for dozens of motors on a single rocket. It's a pathway to the Interplanetary Transport System (BFR). It's the ability to put up giant space telescopes. Etc. Etc. Etc.
"Just a rocket landed" folks, this is what happens when your mind is vandalized by Fox News. You learn to disparage accomplishments by dismissing them as simplistic and insignificant. And you corrupt hope and optimism - with cynicism and distrust.