The thing that makes Goku such a lovable and unique hero is that he is driven by the thrill of an exciting fight. Granted most of his fights have the fate of the universe in the balance but the thing is, he cares more about a good fight and saving the universe is not really at the front of his mind. While most heroes are hesitant and take that risk, Goku is chill.

When he fought Freeza the first time, though he had the chance to go back to earth, he chose to stay not primarily because Freeza would survive the destruction of Planet Namek, but he wanted to have his fun. Some people believe fighters are born. Some believe fighters are made. Goku is a pure case that it can be both. Though born to a warrior race with a power level of 2, through hard training and his warrior’s blood, Goku became the greater fighter.

Goku demonstrates that even though people may have different backgrounds and that their respective ancestors may have committed some sins, people should be proud of their background in their own way. For example, America is composed of people of numerous backgrounds. Granted some Americans may not have been raised based on the ethnic background of their ancestors, it is still a part of who they are and its ok to embrace that, or do what Goku did, forget the past and turn those negatives into positives.

Though initially Goku and the audiences first learn of the Saiya-Jins as tyrants and that Goku did not want to be put in the same group as them, shortly after in the Freeza saga,
we come to learn that the Saiya-Jins were also victims in their own rights. Fearing their
potential and the legend of the Super Saiya-Jin, Freeza just decides to destroy almost every single one of them. Upon learning the truth and with Vegeta dying as he cries, even though Goku was raised on Earth, he takes the responsibility as the (then) last surviving full blooded Saiya-Jin to avenge his race and fulfill the legacy of his race by becoming its greatest warrior and taking it to new levels. Though you can take Goku off planet Vegeta, you can't the planet Vegeta off of his blood. He loves to fight and eat.

Throughout his travels in his life that took him from every corner to his world, the afterlife, and the universe, Goku will always be that country boy. Though more emphasized in the Japanese version, despite his exposure to many things, Goku continues to be rather childish throughout his lifetime. This is expressed through his voice actress, Nozawa Masako.

Though Goku’s Japanese casting has been and will continue to be a source of debate for years to come to non-Japanese fans, you can blame Toriyama-sensei for that. When Nozawa auditioned, Toriyama-sensei said that her performance is how he imagined Goku would sound like. Though that was during a time when Goku was a child, but some fans believe the voice is a good representation that he will always be that child.

As an extension to his Saiya-Jin heritage, you can't take the mountain off of Goku. As demonstrated in the seventh movie of DBZ when Chichi and Goku take Gohan to be tested for acceptance into a private high school, Chichi tries to educate Goku on being a regular Joe by saying his hobbies are reading and sports, but Goku just says he wants to say fighting is.

Though it was mentioned earlier that he loves to fight despite the stakes, at the same time, he does know the consequences of his actions. Despite having the chance to be revived by the Namekian Dragon Balls upon the end of the Cell saga, Goku refuses to be brought back to life because there will be people who might have vendettas against him like Freeza (who came to earth to fight Goku) and Dr. Gero (who created the androids for the loss of his organization, The Red Ribbon Army).

At the same time, he knows what his limits are, or maybe it's him getting old upon Battle of the Gods, but when he fought Beerus, despite the fate of the Earth hanging in the balance, Goku came to terms that he was not strong enough to beat Beerus and that his universe is a small part of something much bigger. However, Beerus acknowledges Goku as his second strongest opponent ever behind his martial arts master and personal assistant, Whis. Goku demonstrates no regret and uses the defeat as a motivation to become stronger.

This is the scene in Dragon Ball Z when comparing both the Japanese and English versions show not only just a mere performance difference, but a culture difference. Though the Japanese version of Goku turning SSJ for the first time is more emphatic on the emotional aspects, the dub tries to make it more heroic. When Goku emerges the clouds and dust in the English version in his SSJ form, he says “I am the hope of the universe. I am the answer to all living things that cry out for peace. I am the protector of the innocent. I am the light in the darkness. I am truth. Ally to good! Nightmare to you!”

The reason why there is a cultural difference is this quote demonstrates how westerners and Japanese define a hero. While Americans like to see a hero be all bad ass, beat the bad guy, and come out on top, the Japanese are more about someone who perseveres against impossible odds or even dies in the process.