God could have told

 Somebody else to build the ark there was other people 

God didn't tell you to build a ark

 He told Noah 

Idk

 How much time passed between the first chapter and 8 pages into the first book of the Bible that Moses wrote but page wise 

By page 8

 In this Bible brought the waters back to 

God

 Who in the very first paragraph in the Bible divided the waters