I assume you mean people are "evolutionary adapted to" eat meat. That's of course a fact. Whether an organism is a carnivore, herbivore or omnivore is a characteristic that is based on observations. Organisms do whatever they do to survive and reproduce. An organism that is part of a species considered omnivore changing its diet to a vegan diet doesn't contradict that. Organisms do whatever the basic laws of nature allows them to do.
So I just think people should realize that this is neither an argument for veganism/eating meat than it is one.
Humans are also "designed" (as you would say it) to be extremely effective at murdering each other. I think you would agree that this should not have any bearings on what we should, as society, consider morally acceptable. (note: I am NOT saying this is equivalent to eating meat, I am just saying that empirical observations on the humans as a species shouldn't have any bearings what we deem morally right/wrong!)
Don't worry I'll dissect your reply one by one with facts.
Needless to say "our ancestors" covers a very broad range of organisms; it goes from your parents all the way up to from the very first single-celled form of life that formed 4.25 billion years ago. It's easy to imagine that a lot of change can occur over such an enormous periode of time. We know there's such as evolution of course, right. It can also go very fast. (but we also know that it can occur over a very short amount of time, significant evolutionary adaptions in response to different available food sources have been observed to occur over just a couple of decades in a species of lizard e.g. :
https://www.sciencedaily.com/releases/2008/04/080417112433.htm )
Assuming you're talking about the more recent human ancestors from the genera australopithecus and later of course homo, then first of all it should be noted that the exact dietary make-up is not completely known and would of course likely vary based on specific population, point in time, season, geography, climate. Organisms that are struggling to survive generally eat whatevery they can find that is somewhat palatable (which is even more true for omnivorous organisms that early australopithecus and homo species were)
But, even based on what we do know, it is generally considered among paleontologists that fruits and plants were dietary staples and that meat in some degree was eaten from 3 to 2 million years ago.
The vegetables we eat today exist because our ancestors at some point cultivated them because they ate them.. Do you think humans from tens of thousands of years ago were really just all the way selectively breeding vegetables just so the only humans that live today would have vegetables to eat? Of course not. They started cultivating them because they were already eating their wild ancestors..
Real edible wild fruits and vegetables are rare? What a load of nonsense. How many edible plants or parts of plants that are edible is an interesting question, on which there's surprisingly little data, not even estimates. There are 290 000 known species of angiosperma (flowering, fruiting plants) in the world... According to the FAO there are at least 20 000 known edible plants in the world, but keep in mind we don't even know exactly might be edible. Most plants simply have not been studied scientifically to assess their edibility, because we rely on a few key species for worldwide food production (the same goes for animals too by the way).
