I did deep research on this some time ago, and concluded that the WTS did not say that jws had to be vegan or vegetarians at this time, and that other jws could make their own choice but not insist others had to. As to the so-called new system...nothing is clear per the WTS. As to Adam and Eve, Abel sacrificed some of his sheep to god in Genesis, so they obviously killed animals. Did they eat them, it does not say. As to why god let humans eat animals properly bled after the flood, the WTS has some guesses, but again the bible does not say. I'll try to find that research. The WTS has a pattern. June 8, 1976 Awake p. 14-15 "To the question, ‘Should worshipers of God be vegetarians?’ the answer must be that it is an individual, personal matter. If a person is convinced of the value of it from the standpoint of cost, economics or health, and finds it practical, he may adopt a vegetarian regimen. But he cannot find ethical support for his restricted diet in God’s Word. If he becomes involved in that aspect of vegetarianism, he is losing sight of God’s way of viewing things." AND August 8, 1997, p.18; "Because of health, economics, ecology, or compassion for animals, a person may choose to follow a vegetarian regimen. But he must recognize it as only one way of eating. He should not criticize those who choose to eat meat, just as one who eats meat should not condemn a vegetarian. Eating meat or refraining from it does not make one a better person. (Romans 14:1-17) Neither should one’s diet become the prime concern in his life. “Man must live,” Jesus said, “not on bread alone, but on every utterance coming forth through Jehovah’s mouth.”—Matthew 4:4."
And Watchtower January 15, 2002, p. 23 "In order to thrive, sheep need human care. Abel’s occupation testifies that man raised these domestic animals from the outset of mankind’s history. The Scriptures do not say whether the earliest humans used animal milk as a source of food, but even those with a vegetarian diet can use sheep’s wool. And when sheep die, their hides serve useful purposes. To clothe Adam and Eve, for instance, Jehovah provided “long garments of skin.”—Genesis 3:21.
In any case, it seems reasonable to assume that Cain and Abel originally cooperated with each other. They produced something that others in the family needed in order to keep clothed and well fed."
As to the animals were vegetarians, the study of animals and their characteristics does not support the idea that lions and tigers eat vegetarian, their teeth etc. proves they are designed or evolved to eat meat. That's my opinion. BTW the about above, I am reporting not supporting.