Before we go into those, just remember that, obviously, there wasn’t something like a video crew documenting the creation of the world. We don’t have eyewitness accounts, and so our scientists have had to figure out how the world came to be based on their observations, discoveries, things they’ve dug up, and techniques like radiometric dating and DNA sequencing. As more things are discovered, and better technology is developed, our scientific theories evolve. And they will continue to evolve! The science we study in school today is not the exact same science our parents learned decades ago, and our kids and grandkids will surely be learning about different things as well. So the theories that you’re learning now are just our best explanations based on the things we know so far.