If Adam and Eve were vegetarians at the start why and how did it all change?

 

Everything was made ‘very good’: perfect (Genesis Ch 1 v31).  There was no death.  All creation lived in harmony.  But when Adam and Eve turned from their Creator in rebellion sin entered the world and death became a natural part of the ‘fallen’ world.  God actually made clothes out of animal skins for Adam and Eve after they had sinned (Genesis Ch 3 v 21).  So from then on survival of the fittest began and animals were allowed to be killed by Man, though he still had a responsibility to be a good and caring steward of all of God’s creation.