I am Uatu, The Watcher.
I have been charged with observing your world since before humanity reigned as the dominant species, but in the the same orbit, in other times and places, lie other Earths, and to observe them is my duty too. We know them as alternate universes; With every choice you make, you literally create a world. History branches in two, creating one Earth where you made the choice, and a second where you didn't. That's the secret of the universe; billions of people, billions of animals, making billions of choices, creating infinite Earths. Some so similar to each other that you could spend a lifetime searching for any distinction. Others so radically different, they defy comprehension.
Our time is short, so we will focus on one only, the one known by the designation Earth-28902.
As if a mirror image, it's not that different from the world you previously knew as the only real one: The technology and civilization on a global scale remains the same, and the same wars and battles were fought and won by the same people commanded by the same leaders. People are able to be born with superhuman powers or acquire them later in life, and both "superheroes" and "supervillains" prowl the streets of their cities hidden behind masks and helmets. I wasn't there yet to observe, so i do not know what led it on it's path, but it is somewhat refreshing next to all the others following a same formula.
The only major difference to those Earths, the one that has set all the other differences into motion in the first place, is the roles these heroes and villains play. Whatever occurence sent Earth-28902 into it's orbit millions or maybe just thousands of years ago led to an universe where the world's greatest heroes became it's greatest threats. But, as there will never not be heroes, other people rose to their place. These new heroes were, interestingly, known to most other worlds as their worst villains. From those points of divergence, this Earth developed into the one you're seeing before you. It Is indeed interesting how far can a single detail go in the grand scheme of things.
I have watched one man in particular, known as Quentin Beck and better, but not yet, as Mysterio. Every other Mysterio's path has led to loss and ruin, thus i am not very optimistic about his fate, but who's to know the designs of One-Above-All? The chance of universes like this occuring is infinitely small and this is most likely the only one i'll ever get to document, so i have to admit i'm curious. We have to wait and observe the course this world will take.