If you follow the literal text of Genesis, everyone before Noah was a
vegan. Adam and Eve, pre-Fall, are told they can eat all naturally
growing fruits and vegetables [possibly this envisages a Golden Age in
which grains and other tilled products grew without human effort].
Post-fall they are told they will have to get food the  hard way, by
agricultural efforts.  Only when Noah disembarks from the Ark is meat
explicitly put on the list of permitted foods.   And then at Sinai come
the lists of permitted and forbidden foods:  quadrupeds, fish, fowl,
insects all have  entries in both categories.  And quite forbidden is any
animal that has died naturally or by hunting [this latter does not apply
to fish, only to quadrupeds and fowl].   The permitted categories
are generally domesticated animals,  and exclude most predators and
scavengers.  The Biblical milieu obviously had a settled agriculture with
domesticated livestock as its ideal.
There are two hints that meat was eaten before Noah:  the statement that
man is to have "dominion" over all the animals, and the fact that by the
time of Abel and Cain livestock was being tended in herds.   Make of it
what you will....

  Jeffrey Smith       [log in to unmask]
O voi ch'avete li 'ntelletti sani/mirate la dottrina che s'asconde/sotto
'l velame de li versi strani [O you of sound thought, see the doctrine
which hides under the veil of strange verses]--Dante, Inferno, Canto IX