I’m not a vegan and probably never will be one. But there are a lot of things worth considering, regarding diet.
Jesus declared all foods clean. This means that nothing I eat is going to have some sort of spiritual affect on me. So, decisions I make about what I eat should be made based on other considerations.
With that question completely off the table, we are left with considerations such as:
Health: Seems rational to eat healthy. Take good care of yourself. But veganism does not solve this for everyone. All the plant based protein sources I know of would give my husband permanent migraines. Veganism is simply off the table for him. Diabetics also have quite limited choices about plant-based protein sources, because there are so many carbs in most of them.
Income: What people eat is often determined by what they can afford to eat.
Income again: Preparing fresh animal products takes much more care in storage and preparation. If you don’t have the resources to store, prepare, cook, and again store meat or dairy items, then you will probably not be working with the fresh items. Although animal products prepared for long shelf lives could fit into your life and therefore diet.
Preference: It seems reasonable to be able to eat some things you like.
Morality/Cultural norms: Although we often deny it, culture plays a HUGE role in what we eat and would recognize as food. For example, blood is a common ingredient in some countries. In the US eating blood seems not only distasteful but to some, immoral.
Personal moral choices: Some of my friends find the damage to the environment and the harm to animals that is part of the meat industry to outweigh any pleasure or benefit they would receive for eating meat. If this is important to you, then you shouldn’t eat meat. My friends would also point out that if it isn’t important to you, you are underinformed and haven’t thought about the issue enough.
Apex Predators: We are apex predators. We don’t like to see ourselves as such, though. Unrefined. Too closely associated with our ancient, more animalistic roots. We don’t like to see ourselves as animals.
Cannibalism is a particular type of predation - of one’s own species. No one imagines turkey vultures as cannibals, when they’re dining in my road on roadkill raccoons. Cannibalism for humans would be eating other humans. There is no “sort of “ cannibalism. What we don’t like about this picture is seeing ourselves as somehow similar to the turkey vultures.
These are just a few considerations. I’m sure there are more.