So we know - do we?

Someone showed me an intriguing mental exercise once. They wrote a shape on paper, basically like the letter H - except the way they wrote it was with plain straight lines, no font or style, and then asked "What is that?" One obvious answer is that it's the letter H. That is, if you use the same Alphabet that we do in English. To someone who spoke and wrote Russian, and used the Cyrillic Alphabet, it would be the letter that signifies the sound 'N' If you write the name "Nicholas" in Russian it starts with what we use as the letter 'H'. Right. So suddenly it's not so simple. Then again, it could be a drawing of rugby football goalposts. It could be a picture of a tree trunk with a piece of rope tied round it. And without going on too long, the point is this: what you make of it depends on what your mind has already been trained to see it as.
If someone said to you, "Ich bin auschlander. Nicht verstehen" then you might not know what to make of it at all - unless you speak German, in which case you know that it means: "I'm a foreigner. I don't understand." (Apologies if my spelling is not perfect in German).
Try this: (and again, the spelling could be a bit wonky) "Shin,a'weel, a'nish."
If it means nothing to you, that's not surprising. I've been told that it is a Gaelic phrase, from Scotland, meaning "That is the way that it is," said as a fatalistic expression of acceptance or exasperation.
You know what it means if you speak the language. The point here is that you have to know some things before you can understand others. And for that reason, it can be quite wrong to say, "The facts speak for themselves." What happens is, the facts speak according to what you already know.
And people can be misled. The people of Ancient Greece were intelligent and inquiring; they sought to find the explanations for things; and they theorised that waste material and rubbish gave rise by spontaneous generation to flies, because that was how it seemed.
More recently, it was believed that stomach ulcers were caused by stress or bad diet, and diet was the only way to correct them. Not long ago, researchers found out that they can be caused by a bacterium, and can be treated with a specific medicine. It was good too, because for years people afflicted with ulcers had to live on this bland miserable diet of things like boiled fish. I can remember one of my aunts having to live that way. Not fun! But here's the point. Very intelligent and qualified people were mistaken in what they believed.
I could admit to some of the dopey mistaken ideas I've had at times, too, but then I'm not an expert who got believed by thousands of others.
It was once believed that if a human being travelled at over forty miles an hour it would kill them.
It was once taught that the Earth was the centre of the Universe. The best minds of the time thought they had deduced that, and it was accepted as knowledge.
Once it a while, what all the best and brightest told us has been found out as incorrect. It's worth keeping in mind. Of course, we have to rely on some things we're told or learn, or we can't get on with life. But sometimes what is "Truth" seems to undergo change.
I wonder if one day it will be shown that the human species did NOT evolve from other life forms?