Great article. It reminds me of the grade school mentality that most people have regarding Henry Ford - that he invented the automobile. What he did was apply the concept of the assembly line, which already existed, to the manufacture of cars, which already existed. And he applied it to a design that was inexpensive enough to enable the sale of the high volumes the assembly line produced.
If he didn’t do it, someone else would have. It is amazing what competition motivates people to do.
One does not have to ascribed to the Great Man theory of history to know that individuals do matter. Yogi Berra is said to have said, when you come to a fork in the road, take it. Two roads diverged in a yellow wood, but do all roads end up in the same place? Would McClellan have been a better choice in 1864 than Lincoln? We will never know. But likely things would not have been the same.