Like the Battles of Marathon and Thermopylae, Salamis has gained something of a 'legendary' status (unlike, for instance, the more decisive Battle of Plataea), perhaps because of the desperate circumstances and the unlikely odds. A significant number of historians have stated that Salamis is one of the most significant battles in human history (though the same is often stated of Marathon). In a more extreme form of this argument, some historians argue that if the Greeks had lost at Salamis, the ensuing conquest of Greece by the Persians would have effectively stifled the growth of Western Civilization as we know it. This view is based on the premise that much of modern Western society, such as philosophy, science, personal freedom and democracy are rooted in the legacy of Ancient Greece. Thus, this school of thought argues that, given the domination of much of modern history by Western Civilization, Persian domination of Greece might have changed the whole trajectory of human history. It is also worth mentioning that the celebrated blossoming of hugely influential Athenian culture occurred only after the Persian wars were won.

From: https://en.wikipedia.org/wiki/Battle_of_Salamis
What about the battle of Salamis (fought in 480 BC), do many historians believe make it one of the most significant battles of human history?
The battle (fought between the Persian Empire and Greek City-States in 480 BC) is still considered by many historians to be a foundational event in the development of Western Civilization and modern Democracy.  Some say that if the Greeks had lost at Salamis it could have had profound effects on the trajectory of human history.  Historian's trace back much of today's Western ideals in philosophy, culture, politics, and science to Ancient Greece.  They deduce that if Persia had won the Greco-Persian wars it could have oppressed the blossoming of many modern Western schools of thought.  

Salamis is one of many skirmishes fought over the course of almost half a century during this conflict.  There were other pivotal battles that contributed to the Greek victory, like Marathon and Plataea.  However, if Salamis had been won by the Persians, the Greek navy would have been unable to stop them from establishing beachheads across Greece.  Much of the Greek victory has been attributed to their use of the environment to their advantage; leveraging natural chokepoints (like at Salamis) to reduce the effectiveness of Persia's numerical advantage.  Had Salamis fallen to the Persians it's reasonable to assume that this strategy would have failed and Persia's massive armies would have been able to dominate the Greeks.  

It's also impossible to predict the outcome of the war if Persia had won this battle, even though chances are things would have ended very differently.  Salamis is perhaps more highly regarded because of the long odds the Greek navy faced.  They were able to prevail despite being largely outnumbered, which could also be why it's considered such a remarkable event.