Call me blasphemous for trying to mimic the legendary Plato, but I think it’s worth a try.
Consider a massive beach ball, divided into six colors, that exists in the center of a great landmass. The beach ball is so massive that everyone on the land mass can see it, no matter were they are. Now suppose that the landmass was divided into six countries respective to which of the six colors of the beach ball the people could see. Such is depicted in the following image:

If you were to ask someone from country A, “What is the color of the beach ball?” they would respond, “Red.” Likewise, if you were to ask someone from country D, “What is the color of the beach ball?” they would answer, “Green.” The same is true for every country, they would all answer based on the only color they could see.
Now suppose that someone from country A traveled to country D and met one of its citizens. The two would debate about what the true color of the beach ball is. Now suppose even further that during the traveler’s entire stay in country D, he refused to look at the beach ball while he was there, insisting that the color of the beach ball as seen from his country was right, and what the citizen of country D claimed to be the color of the beach ball was wrong.
Now you might say to yourself that this is an unusual circumstance, and these are unusual people, but to that, I say, “They are not so different from us.”
Now suppose you were to ask me, “What is the color of the beach ball?” Based on my perspective, I would answer, “Red, Orange, Yellow, Green, Blue, Purple, and White.” Thus, no member of the great landmass can know the true color of the beach ball without seeing it from everyone’s perspective.