Which foods are “normal” can reasonably be defined in three ways; which foods are eaten most, which foods most people eat globally, and which foods most people eat locally. Worldwide, an estimated 2 billion people live primarily on a meat-based diet, while an estimated 4 billion live primarily on a plant-based diet. If what is “normal” is defined as what the majority of people do, then more people live primarily plant-based than primarily meat-based, making plant based diets more “normal” than meat-based diets, strictly speaking.
However, which foods are “normal” can just as easily be defined as which foods are eaten most. In this case, in the Chinese-Japanese, Australian, Hindustani, Central Asian, Near Eastern, Mediterranean, European-Siberian, South American, North American, Central American and Mexican regions, every single staple food is vegan; staple being defined as a food that is eaten regularly and in such quantities as to constitute the dominant part of a person’s diet and supply a major proportion of their energy and nutrient needs. In fact, just 13.5% of food eaten globally is composed of meat, milk, fish or eggs.
If this argument is going to work, we then have to rely on the third definition of normality, simply stating that meat is normal because most people eat meat here. The flaws in this logic should be obvious. This is extremely western-centric; it is arguing that despite the fact that more people globally subsist on plant based diets, the fact that many of us eat meat-based diets here makes it more normal than anything anyone else does anywhere. What is normal is solely defined by rich western countries and what everyone else does simply does not matter. If you are happy with this thinking then eating meat absolutely is normal. However, that still does not make it ethical. This argument is built on the logical fallacy of argumentum ad populum; this argument holds that the proposition that eating meat is ethical is true because many or most people believe it. This has no rational basis and is a poor way to argue.
Furthermore, we must acknowledge that just because a behaviour is widely practiced does not justify continuing the behaviour regardless of how harmful it is. Discrimination based on race and gender is widely prevalent across many societies, so is forced marriage, so is female genital mutilation; that does not make any of these practices any less unethical. If the entire population decided that dog-fighting was now ethical, and it became widely practiced by everyone, this would not make dog-fighting ethical. I am not claiming that eating meat is the same as any of these things, but I am pointing out that this argument simply does not work as an ethical justification for any behaviour. What is “normal” is of no ethical relevance whatsoever.