It has been done again. And again and again and again. But the first landing is most famous because, well 1st time on moon! But you just don't hear about the less important landings that took place afterwards.
Personally, I don't know for sure. I wasn't there but there are excellent arguments in both camps saying yes we did and no we didn't. I expect we haven't been back because there is nothing left to learn and that money can be spent on other explorations.
I wonder sometimes. How did they take pictures of the ship and Armstrong's first step from outside without someone setting up a camera? And why can't you see the flag with a telescope? How did they get past the Magnetosphere without getting radiation sickness? Cancer later?