And you keep using different names to describe them. As you should. Communism is not one thing and never was. But when people refer to base or true communism, the answer is just one.
It's how it was defined in the communist manifesto in 1848. You could say it's Marxism, but I dislike that naming since others played a big role on forming it as well, like Engels and others who based on Marx's mostly economic study added the philosophical and political angles.
Every theme or name change after the manifesto (that is not found in later revisions by the communist international) is attempts at adapting it with different angles and for different purposes and circumstances, aka NOT base or pure communism. Don't bundle everything in one basket and try to make sense, same way that bundling Putin's Russian form of Capitalism with US's imperialism and French Revolution's early capitalism together doesn't make sense either.
He asked for pure communism, I answered for that. If he asked about Trotsky, I'd focus more on the permanent revolution and the Fourth International. If he asked of Stalin, I'd talk about his socialism in one country theory
I'm not quite sure how to reply to that, because you make some good points. I flatly disagree that communism can't work. It's like saying Capitalism couldn't work because for a whole century the French revolution was failing before 1789. Which is not even the first humanity's attempt for a capitalist system, but the first well known one. We still have ways to go and failed attempts to try to get it right.
However, the most important thing in my eyes is to learn from the past. Being in a country that was surrounded by communism, tried, and was refused help from the then socialist states, I know very many people that still look back to those times with fondness. From my country and neighboring ones that were parts of the socialist block. But all those implementations had their problems and these same people would be the first to admit that. Our job is to go through all that history and judge it with clear heads, see where it went wrong and how or why, so in the next attempts we'll fail in a different way, until we get it right. Similar to how every socioeconomically system did so far.
I don't care about Anarchy or Socialism or Trotskyism or whatever, as long as it gets us to the end goal of a classless system without economic or power elites that see us as data nodes to profit off. Each of those approaches has its pros and cons and there are many others as well.
But saying it failed so we best move on, because the first handful of attempts went wrong is not going to bring any change whatsoever.