Is every single body in the world intended to be within the so-called healthy BMI range?

I don't think "every single body in the world" is meant to be within the healthy BMI range...
However, for the average people who are trying to lose weight, it is a good guideline to start with.
Also, while there are always a few "outliers" with anything; I do feel that most people who consider themselves as outliers actually aren't and would benefit from dropping that rationale (at least for a little while) to see if maybe they were only using it as rationalization for not succeeding. I know I've done that before, and a lot of us probably have.

The short answer is: No.

A slightly longer answer:

All these B*I's are gross estimates. They measure certain attributes of the human body that in the whole of human population distribute on the famous bell curve. Then they are correlated with a rather vague notion of health and fitness. So clearly the final outcome of all this process does not say much on the desired weight or calorie consumption or exercise routine of a specific individual.

The only sensible way to look at BMI and other human body indicators, is as something that gives you a very groos feedback on your fitness related decisions and choices. When monitoring them is incorporated with a true understanding of your own body and your personal fitness goals, it does help you allot to keep on track. What you shouldn't do is to comare "yours" to "theirs" or to some arbitrary standard. Your fitness is your concern and you should take care of your body because it is yours.