One quick thing I would add is, "NO" nature would not keep making them. It is only our direct action that props up these artificially selected species (q.v., hybrids that require us to actively produce them, or your favorite variety of apple which is a clone of some great-grandparent tree or the fact that these crops would not compete well with other plants because we've selected them for their food production, not overall hardiness. They'd be out competed. They put too much of their energy into producing stuff that doesn't optimally help produce a new generation, and thus require our tending).
Your statement is a bit like saying "if we disappeared tomorrow nature would keep making sheep." Probably not (at least medium term). Sheep generally require our protection to avoid being killed. It probably wouldn't take long for a predator species to take hold in a given area and kill them all.
Sure, the banana is a selectively bred, sterile monocrop but the candy is made of 20 ingredients, resembling nothing found in nature in composition and nutrition.
Simplistic heuristics have failed hard before in nutrition, so why do we keep repeating the new ones?
The only one that makes any sense is "Eat food, not too much, and mostly fruit and veg".
Michael Pollan, who promoted (and possibly introduced) that slogan in his book In Defense of Food, goes on to explain that "Eat food" means more specifically "don't eat anything your great-grandmother wouldn't recognize as food" (p. 148). In short, he agrees exactly with Jack Lalanne: avoid processed foods.
If you consider it as a heuristic instead of taking it literally, your objection about artificial selection of produce is also more or less irrelevant. Man had a hand in shaping those plants' current genome, but if we disappeared tomorrow nature would keep making (most of) them. It's still easy to distinguish from, say, donuts and still useful as a heuristic.