the bioanthropology says our ancestors ate animals and the other carnivores as well, this through chemical testing.
even from the beginning, cains crops were rejected by god while abels flocks were accepted by god. then when moses came along, when people had to sacrifice for their sins, they didnt bring fruits and berries and nuts. no, when one is paying for sins the payment must be something you value, not something that you can do without anyway. the bigger the sin, the more the meat, especially fat. we are made in gods image and after his likeness. he particularly likes the organs and the fat around them. lots and lots of fat. unless you think the creator was just pretending with moses.