Heracles was never just a mere mortal. He was born with a divine blood. His father is the greatest god of all, Zeus. But he was still mortal. One thing that makes the end of Heracles' life stick out from the rest is the fact that he becomes a god. Heracles eventually heads up to Mount Olympus and becomes immortal. Not all heroes get to be gods, so this is an extra super special event.
There are conflicting reports about when, exactly, Heracles headed up to the land of the gods. Some say that he became a god after completing his Twelve Labors. Others say that he became a god after a period of wandering around and marrying lots of different women. In fact, it seems like the only thing people can agree upon is that Heracles did, at some point, make it to the land of nectar and ambrosia.