Killing even one human is worse than killing any number of bison
Do you have any verifiable proof of that, or is it only because you are a member of the dominant species and that is the viewpoint of your species?
I agree that the Passenger pigeon should be first on the list, just above the bison.
your article noted that the bison didn't care when their families were shot down. People do.
This might help you make your list:
https://www.thoughtco.com/recently-extinct-animals-1092157
and there is this:
"According to the research, published today (Jan. 29) in the journal Nature Communications, cats kill between 1.4 billion and 3.7 billion birds and between 6.9 billion and 20.7 billion small mammals, such as meadow voles and chipmunks."
https://www.livescience.com/26670-cats-kill-billions-animals.html