It's strange to think we chose to hunt or raise large animals; and to perform all that such a choice implies i.e. growing plants to feed them and more generally farming, when we could just raise ants and plants.
It is also much easier to capture and butcher a cow than the equivalent mass/protein of ants.
Plus ants can't provide all the nutrients we need.
Animals are expert foragers. A deer can get to 200lbs or more eating what a deer tends to eat just fine. You will struggle to forage like a deer in that same environment, but you can coopt the deer's superior foraging abilities by simply eating it. And if you have a herd of animals you shepherd, not only are they making use of biomass you can't yourself make use off, but they are acting as a store of biomass keeping it fresh and available until you decide to cull some of the herd.
I think I can live off just the fire ants in my yard. Not to mention all the neighbors. Even with constantly baiting them, it's hard not have at least 1 hill active at all times during the summer, as the neighbors are dumb and just spray. So they just end up moving.