There are some things that need to be corrected.

1. Apes are omnivores . They eat meat, insects, vegetables, fruit, etc. They eat whatever food source is available. They have eaten animals as well as monkeys. Also, they have canines to be able to rip flesh, further proof they are omnivores. You can tell the diet of a species by the structure of its mouth and and structure of its teeth. Herbivores have no canines to rip meat. The just have teeth to chew or munch plants. Take army ants, they kill and eat anything in its path, because they have powerful mandibles. Humans are the same, we eat whatever food source that is available, but unlike animals we don’t have the ability to generate vitamins, so we have to eat food that provides those nutrients. Which is why a variety diet of protein, fat, carbs, and vitamin and minerals are necessary. However, protein, which is the main nutrient that all animals ( humans,etc)!need, because the body does not store protein and it is the building block of life. Animal (meat) protein is complete in essential amino acids. Plant protein is not. There is no plant that provides your essential amino acids like meat.

2. A lion can generate most of the vitamins that it needs, as well as produce amino acids. However, they don’t produce all the amino acids that they need, or b12 I believe , this is why they need to eat meat, and don’t need to eat plants. So their diet and eating is based on the biological make up of their body. Same for cows and horses , they don’t have the ability to digest or metabolize meat, so they are herbivores. You eat and feed based on what your body can metabolize and digest ( pull nutrients from), and based on your nutritional needs.

3. Indigenous people and tribes were Hunter/ gathers. That has always been their foundation. Hunting meat ( fish, mammals, birds) and gathering nuts,fruits and vegetables. Aztec, Myans, native Americans, Africans, Egyptians, etc all hunted. But as you stated Europeans brought diseases that none of them had experienced. As you can see that had nothing to do with eating meat, since tribes and indigenous people were already hunters , and some even cannibals. It had more to do with sanitation and hygiene and coming from regions where there was and is different bacteria and viruses. But over time they became immune to them... here is an example: Take the North Sentinel tribe that is protected by the Indian (india) government. The tribe has been in existence for 60,000 years, and the rest of the world is blocked from visiting them. Why? They could actually die from contact with us , due to their bodies not being exposed to the viruses, disease and germs that we have been exposed to. Like chicken pox, flu, stds, etc . No different than what the Europeans brought over from their region.... I caught the chicken pox from my young cousins when I was a damn teenager. It was severe, because it’s worse when you contact it at an older age. It took me close to a month to recover. The point is I had never been exposed to it, so I had no immunity.

4. Scientist are already concerned about glaciers melting that have been existing for centuries, because they might release bacteria and viruses that this civilization has never experienced. And if you think about it , as climate change is getting worse, new viruses are popping up all over. Animals, insects, etc travel farther than humans to all parts of the world, so could they be catching pathogens that are newly released and pass it on?

5. I’m a man of science, so I look at things as organisms and atoms and molecules . A living organism has a cell structure, and plants, animals and humans are all living organisms that consume each other ( there are meat eating plants). All organisms must consume some type of organism to have energy and function. Even if you are plant eater, you’re still killing and consuming a living organism. Being sentient and conscious or having feelings are irrelevant when it comes to energy consuming energy. This whole concept of vegan, vegetarian or meat eater is all meaningless. If you can digest and metabolize it. You can consume it for nutrition.

Also I would like to add. That Cooking meat is highly important to killing bacteria. This is what man discovered and how we were able to really evolve. The appendix in the body l, which is an immune system organ, was highly needed when meat was eaten raw to kill bacteria. We don’t use our appendix like we used to because we now cook our food to kill bacteria. However, eating raw meat leaves you susceptible to eating bad or tainted meat. And this is the real issue as well as as poor sanitation. As organisms we all carry good bacteria to kill bad bacteria especially in our guts, but outside the gut it can be dangerous. This is why if your stomach is punctured or you are shot in the stomach where you gut bacteria leaks Into your blood stream, you can go into sepsis. It’s outside of your stomach. This goes for chickens and salmonella, which is friendly chicken bacteria for chickens, but can be fatal to humans. E. coli in cows, friendly to them, but can be deadly to us. This is why it is important to cook meat well done.