I mostly agree with what you said but I'd like to point out a glitch in your argument about halfway through: where you say "because it has, for millions ... of years."

I'd say that's not valid, because what happened for millions of years is a far cry from what modern agriculture is (mostly) accomplishing: (a) actually establishing food security, and (b) for a freakishly large number of one particular species.

When you say "every single one of your ancestors got enough to eat" you fall victim to survivor bias; we know that many, many of our ancestors' siblings didn't get enough to eat. In fact, humanity nearly died out on one or two occasions, though I'm not sure it was for lack of nutrition.

I also feel that natural, historic ecologic agriculture isn't readily analogous to a model of agriculture that would be feasible today. Consider that part of the historic model was a pyramid of natural predation, i.e. animals that lived off the land and each other, fertilizing the "agriculture" both with their droppings and often their corpses, with humanity skimming off parts of that food chain. Again, I don't think a faithful replication of that model could effectively nourish anything near the world's current population of humans.

I could be wrong, but I suspect that a model of agriculture strongly similar to "historic ecological food production" might only work for a significantly smaller human population.