You pretty much have it

And you said it better than I could've. One should also note that much of the ancient world lived on a limited and highly specialized diet, which is not always healthy. In many parts of the world fresh fruits and veggies were a luxury. Vast improvements in transportation, refrigeration, food processing, etc. have made it easy for people to get access to fairly cheap food. And, unlike much of the world in ancient times, starvation has been virtually eliminated in the world, with only a few exceptions (parts of Africa and Asia.)