How long has Humanity been on Planet Earth?

[Pat Mustard]

 only about 1.6% of human history is recorded.

Currently, the Garden of Eden is at the bottom of the Persian Gulf.  Genesis 2 describes four known rivers flowing out from named locations—in the mountains of Arabia and the mountains surrounding Mesopotamia—and meeting together in the Garden of Eden

The only time these rivers can join together on dry land is when most of the Persian Gulf is dry. The drying up of most of the Persian Gulf requires that Earth be in an ice age.

The garden of Eden doesn't exist. It is a corruption of the Bablyonian/Persian of idea of parādaiĵah where their heaven equivalent was considered the perfect garden.