Are chickens not the most wide spread birds? Sheep and cows the most widespread 'large' animals.
Even rats are doing as well as they are because of humans.
Yes I suppose you can reduce the meaning of life to successfully creating the next generation, that applies equally to humans and amoeba, but I would contend its too reductive.
Almost all that you are eating are plants, taken from the wilderness tens of thousands of years ago, and genetically selected over hundreds of generations.
If you went back to eating the plants in the state they exist naturally in the wilderness, you would have a very hard time feeding yourself.
BTW, vegetable farming, be it organic or conventional (especially conventionnel) isn’t exactly non-human animal friendly.
But still, veganism isn’t as clearcut as it would first seem.