I don't think there is any one particular type of food we can say is good for all human bodies at all times... Some things are not good for you when you're young, and some disagree with you when you're older, not to mention allergies and such stuff.
Having said that, modern nutrition has taught us that fats (especially saturated or trans) and sugars (especially processed) should be consumed in moderation. Perhaps the lesson to be learned here is that the less processed food you eat, the better. It means raw vegetables and fruits, unprocessed meats or minimally processed dairy.
If you're dealing with babies, note that some things should not be given till a certain age (for example babies shouldn't eat honey before they are at least 6 months old). Then again, probably, the best food for human babies is (not surprisingly) human milk :-)