99% of the world's population didn't know squat about Noah, there was no internet back then.
Death is a naturally occurring event, murder is when someone purposely drowns nearly everyone. Did I get that right?
If someone gifts me something, they can't attach conditions on the gift, that's so gauche. If god didn't want me to have free will, I'm guessing that it wouldn't have given me something that it didn't want me to have. What you're trying to do is to find a scapegoat for god's murders so that your fantasy world doesn't collapse on top of you. Not going to well, is it?