We all came from monkeys...

We all came from monkeys (don't be too picky on that). Monkeys and apes in the wildness don't get much chance of eating meat or other forms of animal proteins. But if they have such chances, they will really relish such food. Remember one of the first Jane Godal movies. It was because chimpanzees wanted to reach ants and termites that they made tools with sticks. The need to make suitable tools to chase animals for meat was also one of the activities that led humans to use tools and became the modern intelligent man.

Not much has changed since then. Animal products are and will still be the main source of necessary proteins and vitamins for the majority of population on the Earth. Some people can refuse meat as personal preferrance, but the human race as a whole just could not afford refusing it.