That's not how that works. A few token comparisons detecting no side effects on what is measured does not mean there are zero side effects. "Zero side effects" is something far more difficult to prove and given all the anecdotes running around regarding ex-vegans, people who forget something important on the diet, people feeling better after eliminating a majority of plant-based foods, etc., I wish anyone a lot of luck trying to prove such a bold claim.

We’ve been eating different plants even before we could stand in 2 feet, plants with bad side effects would be known by now, don’t you think?

Do remind me of all the plants we were eating during winter, and all the plant-only diets people have been following for millennia. If you're trying to use a fallacy to make your argument, at least make a convincing one.

Do remind me of side effects of known edible plants. If you wanna be sarcastic at least stay on topic.

Are you even sure that most vegetable you are eating today even existed 500 years ago ?