The human cost of European colonies and exploitations were many, but the main ones were genocide against indigenous people and the cruel process of enslavement of black people.
When the Europeans arrived in the Americas, they took doeças that decimated indigenous tribes. In other cases, direct conflicts between Europeans and Indians also decimated the Indians. After the colonization process was completed, the process of exploring the colonies began. This process essentially employed slave labor imported from Africa.
In short, the human cost of colonization and exploitation is immeasurable, for in addition to thousands of deaths, it has definitely affected the cultures of local Indians and black people.