Answer:
Well it depends on what and who you believe in, And what religion you are.
Like if your christian, (not saying you are just assuming) You would probably belive that god put everything on the earth and created us all. But its all based on who you are and what you believe in.
Step-by-step explanation:
The reason to this is if you go to church for your religion, the pastor will teach you all about what and who you believe in. But There is no direct answer to this question because not many humans were on the earth at the time, and there is so many stories with different facts in them nobody knows witch ones are true.
I hope this helped and answered you question