What causes and consequences of the colonial expansion of Western countries seem to you the most important and why?

Colonizing America and Africa, the colonialists transported many people of African blood to America for work. it was free labor, which is why there are now large numbers of blacks in North America.
The colonialists destroyed many indigenous peoples in North America, which adversely affected their continued survival.
Due to free resources in the colonies, the countries fought many wars for the colonies (but Africa was divided peacefully), this also influenced the emergence of the United States, Spain, Portugal and others, paid the rebels to expel the British Empire from North America.