وَمَا مُحَمَّدٌ إِلَّا رَسُولٌ
Muhammad is only a messenger.
The verse highlights the office of messengership and corrects an unwarranted expectation about it: a messenger is not thereby exempt from mortal life. The point lies in the mistaken inference being resisted, not in a simplistic denial of every other description.
The restriction serves admonition by compelling the addressees to consider the implications of a familiar truth.