Is what we know real?

I was watching the History Channel and there was this show on and they where talking about history, as they do. While they showed an interlocking web the voice-over said that "History is usually taught in sequences, but in fact it is more like a web" and that got me thinking. So try to stay with me here. What I'm thinking is that the web, would be like a spiders web. Spiders webs are very intricate, but if you cut one part/piece of the web, the web is changed forever. The web would never be exactly the same as it was before. So if history is like a web per say, then if one thing was changed in that web, the web would never be the same. If one thing in our history did not happen, we would not be here, as we are today. Every single person on this planet would be a different person. If one person did not exist or one misstep was added to the time stream, we would all be messed up. Not just that one person, all of us because i'm going as far as to say we are all connected. Like the bible say's we are all connected, but in that context it means related by blood, but maybe it could be comprehended as we are all connected like the spider's web. I would go as far as to say that the world is one giant brain. With different working parts, connections between different things so we can become a high functioning person in society. But if one connection was not there, there could be major repercussions. It would effect your life highly.... Now take that concept and apply it to life on this planet compared to another planets. Everything we know on this planet is because there has been a specific set of circumstances that has led to conclusions. These conclusions to us made sense, so we've kept them all these years. But what if Newton wasn't born, or Albert Einstein? Would we know what we know today? Would it be the same material? I would think not because the web would have been altered. That web would have never been the same again. Would we have concluded gravity is what kept us on this earth? Would be have concluded what specifies life? The life we are living at this exact moment is so specific to our set of circumstances, how could we possibly apply what we "know" on this earth to another planet. Another planet that has a complete different set of circumstances, to led to a completely different set of  conclusions. How can we apply what we know as life to another planet, that could have a completely different definition of life. Scientist's ae only looking at the goldy lock zone for possible life, but only for our type of life. But what about other types of life? I'm sure they could live in harsher climates then our squishy carbon based life. I personally cannot even fathom applying what i have been taught to another galaxy our another universe. And further more i cannot say, for certain, anything about other universes at all. These "scientists" that come up with hypothesis' about other galaxies and possible life forms in them, it's all theoretical. Because in my dictionary, if you haven't seen it with your own eyes you shouldn't be spewing non-sense about what you don't know.