I find that difficult to believe, brother...
Look, we are both speculating here.... you speculate that
if there was a "generic man" that they would have been sinless. I speculate that that would be a very unreasonable expectation, given the nature of human beings.
All I'm saying is that there could have been humans (male and female) created on the 6th day... they were told to go out into all the world, be fruitful, multiply, and fill the earth.
Then, God began HIS chosen race of human beings.... sons of God, Adam being the first. Adam, and his wife were placed in the garden, presumably to live there in perpetuity. That does not match up with the 6th day creation of male and female.
Our Bible is the telling of the story of God's chosen people. There could have been thousands of years between the creation, and the placing of Adam into the garden.
This is all purely speculation on my part.... thinking "what if"..... because my theory would explain so many of the differences between science and the creation.