In Gen 1:30 we see that God has given to all living things (plants excluded) permission to eat from every green herb (plant life). This excludes the Tree of the Knowledge of Good and Evil (Gen. 2:17) Remember, there was no death or blood shed at this time, so no people or animals were eating anything that was alive (that is, anything with blood in it). Plants and fruits were used as the only source of food. After the fall of man, sin entered the world and animals began to eat other animals. Blood was shed and death occurred. We find fossils of fish in the process of eating other fish, so this shows that before the great flood, animals were eating each other. Most likely, people were eating animals as well, but God did not give permission for animal consumption until after the flood (Gen 9:3).
Some may ask why dinosaurs have sharp teeth if they did not use them to eat meat. That is a reasonable question, but the presence of sharp teeth do not require that an animal eats meat. Sharp teeth are needed for tearing certain plants and opening certain fruits. Pandas have sharp teeth but they only eat bamboo and vegetation. Bears have sharp teeth but some bears are strictly vegetarian. Some species of bats eat fruit, nectar, insects, small animals, and blood, but you could not determine this by the shape of their teeth.