You can walk today, and it’s likely much safer.
You can eat fresh food and the food today is overall much safer even the processed food. People in the past didn’t had fresh food this didn’t last long they ate processed food which would be preserved. Fresh food was an occasional luxury and even then it would be much less safe than it is today.
Greenhouse gases have no direct impact on health, smoke and pollution does and even London’s historic smog wasn’t nearly as bad as the average cave lung.
Social organization... how exactly does this relates to health again?
Even the worse life style today (health wise) is better than anything you could do in antiquity.
An average life style is considerably healthier.
And if you selectively choose to live the healthiest life style possible in any period nothing in the past beats today.