We believe that when some previous owner dug out the basement and installed the spiral staircase, that they must have installed this board which looks bad next to the original hardwood floors. This board is level with the current hardwood floors, they must have cut through the hardwood floors to install this board.
We are considering laying new floor on top of the current floor, but the hardwood floor that is there now look pretty good so it seems like it would be a waste. We're just unsure of how to repair this part.
We just finished ripping up the blue carpet you see in the image and found this under it.