Actually it means that Jews will make sure that they will not allow such a threat happen to their race again.
Others have appropriated it for their own causes. Do you think that the renowned Meir Kahane was concerned about other genocides. If so, then he was a true humanitarian and philanthropist. Personally, I think he was only referring to Jews.
Wiki:
"Never again" is a phrase or slogan which is associated with the lessons of the Holocaust and other genocides. The slogan was used by liberated prisoners at Buchenwald concentration camp to denounce fascism. It was popularized by Jewish Defense League founder Meir Kahane in his 1971 book, Never Again! A Program for Survival.
The exact meaning of the phrase is debated, including whether it should be used as a particularistic command to avert a second Holocaust of Jews or whether it is a universalist injunction to prevent all forms of genocide.
The phrase is widely used by politicians and writers and it also appears on many Holocaust memorials. It has also been appropriated as a political slogan for other causes, from commemoration of the 1976 Argentine coup, the promotion of gun control or abortion rights, and as an injunction to war on terror after the September 11 attacks.
There absolutely zero dispute or debate when it is in reference to the Holocaust. The debate materializes only when people try to apply it to other events. It's kind of like how "apartheid" has been misappropriated and redefined for the sole purpose of demonizing Israel
It's an amazing coincidence, that in both of those cases, the misappropriation of a term/phrase involves Israel and both in a negative way. It must be the occupation that makes definitions change before our very eyes.
