I recently did a project on an explorer in the 1500's - Vasco da Gama. Here is a video with some background information about him.
Like I mentioned in the "Impact" part of the video, the Portuguese people considered him a hero for finding the sea route to Asia. They thought this because they were dependent on many goods from Asia before the land routes were cut off. Therefore, when da Gama discovered the sea route, they thought that he was a hero for reinstating the trade between the two continents.
But, in Africa and India, da Gama had treated their natives harshly and cruelly and even tortured and killed people there. His reputation spread as a tyrant and this made Portugal's reputation decline too - since da Gama was representing Portugal, the Africans and Indians thought very negatively towards the Portuguese.
So, was Vasco da Gama really a hero or a tyrant?
It depends on what point of view you see it from. Tying into language arts, point of view affects how you see the people in the event. The Portuguese thought he was a hero - the Africans and Indians thought he was a tyrant. These views all depended on da Gama's actions and where they were from.
In conclusion, it all depends on your point of view to assume your opinion of people; in this case, Vasco da Gama. Always consider the other point of view!