one could argue that arabs as a whole constitute a nation, the problem now is that the political entities in the region (states) do not reflect that overarching arab nation at all. they're in a situation that is somewhat similar to that of the 'holy roman empire' in europe - yes there existed a german nation, but it was divided in so many different sovereign states that no unified national will could ever be asserted.
There are a few ways to look at it, all have been tried throughout history:
- pan islamism: Islam is already a totalling, globalist imperialist way. The world is divided into Dar El Islam (house of Islam, also house of peace or submission), and Dar El Harb (house of the sword, guess why). All non Muslim lands are under a sacred duty to migrate to (Hijra), all lands currently controlled by muslims or have been in the past are waqf. This is why Muslims all around the world still have a hard on for Cordoba and Andalus (Sorry Spain bros)
Pan islamism worked well until there was a bug in the system - religious schism. Now you have two sects who are certain they are True Muslims and the other guys aren't. They've been killing each other ever since, because apostasy is a big no no.
The second bug in the system was political power. The second people realized there was clout to be had, a political split was inevitable, hence you had competing Caliphates.
Pan Arabism is just an iteration of political power grifting. Mecca is in Saudi Arabia, the source of Arab culture and Arabs (they're invaders who have illegitimately colonized and converted the natives of countless countries. Hold on).
Arab nationalism is just that in the small.
In truth, Arabs have no notion of nationalism, state or race. They're still tribal. An extended Arab family is a Hamula, several of these make a "tribe". Arab states and countries are mostly fictitious, and identity is mostly familial and local. The Arab states in the middle east are arbitrary borders handed to puppet leaders in return for oil drawn during the mandatory era.
For a variety of reasons, there isn't a rich tradition of poilitics or statecraft in the arab world.
