We came from fish?

My husband and I started watching this documentary show called Walking with Monsters. We found it on Netflix. I believe it's from National Geographic. It told about life on Earth before the Dinosaurs roamed. 530 million years ago two planets collided and made what we know as Earth. There was no life on the land, only in water. As thousands of years pass, some fish developed complex lungs. Limps grew from what were originally fins, and soft eggs formed hard shells to survive on land. Small plants grew to trees and produces Oxygen. With no animals to eat the trees, Oxygen level was higher than it is now. Every living animal; amphibian, reptile, mammal...started as a fish in water. As the environment changed, the living species evolved to survive in it. We will be continuing to watch this show and I am going to recieve more Evolution Documentary. I can't wait to learn more.