We live on a blue marble floating in space. Space is the "out there" that you see at night looking up. Those stars are burning rocks just like our sun. Nothing up there really but rocks flying around and crashing into each other making smaller or bigger rocks. We live on one of these rocks that circles that burning rock we call sun. Our rock has water on it.
Millions and billions of years ago living in this water on this rock were little one-celled animals. Just a circular skin of tissue with little chemical activities within. These single celled animals learned to split themselves in two to make more of themselves. They lived in pools of mucky water like this for millions and billions of years before anything else was on this rock we call earth. This was before man, plants and animals.
Eventually, one of these little living cells was born a little different. With some sort of advantage. Like maybe a tail that could help it move around better in the mucky water. Having an advantage over the other cells without a tail it thrived and living better and longer. It split and produced more of these cells with tails. Eventually all the tailed cells edged out the non-tailed cells and took over. Most of the non-tailed cells disappeared forever or just changed in other ways to survive.
Then one of those tailed cells developed another feature that helped it to live better. Maybe it was a fin that helped give it direction as the tail thrust it forward through the water. This cell with a fin and a tail eventually took over the water environment and the others died off, changed or just remained the same trying to survive.
This happened again and again over millions and billions of years. Before you know it there were all kinds of variations of cells with different feature that helped it to live well and lots of other cells with various features that didn't do so well and died off. The surviving cells got more and more varied and complex. Some developed into multi-celled plants that thrived in the waters and others developed into fish, octopuses and all kinds of animals.
Eventually one of these little multi-celled animals developed legs and it crawled out of the water onto land. It moved about and ate plants and other things that also had made it out of the water onto land. This legged-animal from the sea lived and multiplied and eventually some of them developed their own special features that gave it advantages to survive on the land. Many variations over millions and billions of years developed into all the animals that have ever existed including giraffes, monkeys, grasshoppers, birds and humans.
Features that helped humans to survive were standing up on two legs and then the use of hands that can then grab things like rocks and sticks. Also humans had big brains and could think and plan well how to get their food and make things like shelters.
Eventually humans grouped together at certain places on the earth and learned to grow their food and cooperate with each other forming groups of houses sharing the work of growing the food and then sharing the food to eat with everyone in the group. Humans also hunted and killed other animals to eat.
Humans also discovered with their big brains how to make and control fire. Humans learned to make many other things as well and got better and better at it.
Many thousands of years later these groups had come and gone. Some grew big, others died away. Time passed and eventually grandma and grandpa came into being in one of these groups. Then your mom and dad came into being also and we had you as a baby and now here you are.
And that's how you came to be here.