I think it was God. He/she/it created the potential for negative. But we choose it.
Are you speaking about the demiurge? Negative beings manipulated us in my opinion.
At the time the bible claims? Not that I am aware of.
So when exactly was the Flood? There are two possible ways of calculating the date. David Wright, AiG–U.S., explains.
answersingenesis.org
I do not prove anything to you. I dont know why I should. That is my believe that we have free will as a species.
I think:
free will is violated through interaction with other negative species (probably). Positive species try not to violate it and If people pray to them for help they help, of course.