My point is because we are backed up by breastmilk, we should not worry too much about nutrients, and can very gradually build up a good foundation of eating solids with a view to the day lo is completely weaned...(though bearing in mind that babies seem to know which food they need).
As far as I know, "red meat", chicken, fish, eggs or soy beans (e.g. tofu) provide all essential amino acids. A large variety of vegetables, beans, nuts and grains do combine to form a complete provision.
Prior to 1970s most people in my city relied on soy beans and tofu, greens and brown rice etc. to provide most of the essential nutrients including protein and calcium. Meat was consumed in large amounts only during festivals, and dairy products were considered very "luxury" and "Western" food.