Meanwhile “More than half the U.S. grain and nearly 40 percent of world grain is being fed to livestock rather than being consumed directly by humans.”

Your anecdote makes it sound like animal feed is just a fixed waste cost of growing food for humans.

Correct but at the same time, the grain production wouldn’t be there if humans were the only market for grain and that grain being produced is not for human consumption. No one should think that people are going hungry because grain is being fed to livestock. Our food needs are met by agriculture.