Remember there are two creation stories. The first in Genesis 1-2:2 (traditionally ascribed to P, Priestly) has a particular focus on the exclusivity of temple rite and Sabbath (7-day template). In this version, animals and people only eat vegetation, because in his idealized past blood is never shed not even by animals. Blood is reserved for sacrifices (that only comes later with the Moses Tabernacle story and performed by priests). In his mind therefore, the imagined golden beginning has no blood shed. P picks up again with his version of a Flood story, after which it has God grant humans a carnivorous diet (but does not have Noah do a sacrifice).
In contrast, J (the Yahwist Gen 2:3-) has animals used (skinned for clothes, and sacrificed (Abel and Noah) right from the beginning. J having Abel and Noah doing sacrifices explains why he has 7 pairs of "clean" animals whereas P only has 1 pair of all animals.
The two stories were each idealizations, filled with allegory. They were never supposed to exist side by side, and didn't until a compiler in the Persian period made it so.