The Americas have been drastically changed through colonization and conquest by European peoples, but I will do my best to address this widespread and complex transformation.
Before the arrival of Europeans in the 15th and 16th centuries, First Nations peoples throughout the Americas had a subsistence lifestyle primarily composed of hunting, gathering, and small-scale farming. They practiced their indigenous faiths, experienced a diversity of linguistic and material culture, and while most were rather egalitarian, some were heavily stratified and were lead by god-kings. Though sometimes at the whim of nature, they had successful economies and produced rich material culture, some of which survives today.
When European explorers and colonialists journeyed to the Americas, they captured many slaves, forced conversions, and killed First Nations people through violence and disease. Indigenous life-ways were almost entirely eradicated. The land which First Nations people lived on was taken as property by Europeans and cultivated for the purpose of exporting resources. The Europeans believed that it was their duty to "civilize" and shepherd the indigenous populations of the New World so that they could be saved in heaven after death. This religious ideology was used to promote the economic exploitation of land and people in the Americas, including people captured in Africa and transported as a source of labor.
The colonization of the Americas has almost entirely eliminated the culture, language, and people who are native to these places. European culture and people were transplanted to effectively replace the indigenous cultures. A great diversity of blended cultures exist today, many with influence from the First Nations populations who once lived on the same land. Though the Americas have been developed into many beautiful and thriving societies, it cannot make up for the genocide which began over five hundred years ago. The diversity which once existed was quickly replaced by a rather small selection of European (primarily Italian, Iberian, and English) culture, language, religion, and industry.