Don't take everything for sure, they are just theories. When we (humans as specie) will visit other solar system and some of them will be just forming we will be able to compare this ideas with that process. What the telescopes now can see about the solar systems forming is still not enough because we still are so far away.
Remember that the Hadean period takes the story teller 4.6 billion years back and tells the story of our planet's formation, appearance of the Moon, atmosphere, and water. The Archean period tells about the earliest life on Earth, its ancient continents, and how bacteria transformed the atmosphere on our planet. The Proterozoic period covers catastrophic global glaciations known as the Snowball Earth, the appearance of eukaryotes, as well as first plants and animals. It also tells about mysterious organisms from the Ediacaran period.
The conclusion is already known by many people that have studied or who have watched documentaries like this one: the Earth have changed a lot in the last 4,6 billion years.
