You are correct, Adam and Eve did not eat meat.
God only gave man permission to eat animals to Noah after the flood. Because the entire nature of the world had changed from what it was, and man would no longer to be able to survive on plant life alone.
There is no way in today’s post-flood world you can get all your nutritional needs from a total plant-based diet. Vegans are not healthy people and usually have more than one element, mineral and/or vitamin they are deficient in.
When my son was in public school there was another child who’s parents were vegan. He was significantly smaller than other children his age. His mental development was slow as well. Very sad