There's also the fact that the creation account in Genesis says nothing about Adam and Eve being vegetarians. Yahweh does say "you may eat from every tree of the garden", but this is immediately before warning them against eating from the forbidden tree, giving the impression that his former statement was simply to distinguish between the trees they could eat from and those they could not.

Furthermore, when they realized they were naked, Yahweh made them garments of skin. Garments wear out. Adam and Eve supposedly lived well into their 900's. They would have had to replace their clothes. In order to replace their clothes, they would have had to kill more animals. If they did not also eat them, that would be wasteful.

There's also the fact that Abel, who lived before Noah and before the scripture where Yahweh tells Noah that he may eat animals (and vegetation. Guess he ate dirt before that), was a shepherd. What would have been the point of raising sheep if you could not eat them? Wool? Would wool farming have been a profitable business venture for a primitive man living in a population of <15 in Africa or the middle-east, where it is always hot ? I think not. And remember also that when he gave his much-loved sacrifice to Yahweh alongside his brother Cain, the account says that he sacrificed a sheep "even from their fat ones". Why would that have been significant if he was not eating the sheep as well?

There is also the little fact that a vegetarian diet would have been physically impossible for humans before the advent of modern vitamin supplements, agricultural methods, and food transportation. Sin perhaps changed us (in the context of scripture), but there is no scriptural reason to believe that it fundamentally altered our basic biology. If we cannot synthesize our own B12 vitamins or break down cellulose in our single-chambered stomachs today, then there is no reason to believe that Adam or Eve could either.