Analyze the cultural impact of imperialist ambitions on imperialist nations themselves. How did colonization and territorial expansion shape nations of race and ethnicity there?

The dedication to imperialism and its pursuits did indeed have a strong and palpable effect on the imperialistic nations themselves. Let's examine some of the major ways in which imperialistic nations and their populations were affected and influenced.
New Imperialism in the latter part of the nineteenth century was brought on through a keen feeling of competition among the world's major powers at the time. Some of the major players of the period include Great Britain, France, Germany, Belgium, Japan, and the United States. The cultures of these and other nations would be influenced in a number of ways. This included strong feelings of competition between these nations themselves.
Colonizing other peoples and nations brings a lot of cheap resources and goods back to the colonizing power. Throughout the late nineteenth and into the early twentieth centuries, a growing middle class developed. These people were able to enjoy goods from far away that increased their standard of living and also their prestige. Even somewhat modest households were able to have objects like Chinese porcelain and Indian cotton as a result of trade and labor conditions in overseas colonies that made these consumer items easily available to them. This, combined with rising wages at home, resulted in a thriving consumer culture.
The drive for imperialistic pursuits also led to feelings of cultural superiority at home. Many Europeans and Americans began to feel that they must be superior to many peoples overseas. Why else would they be in control of them? This was further supported by the now debunked theory of Social Darwinism which applied the concepts of natural selection and survival of the fittest to human society.
One other common result of colonialism is that members of the colonized population would come to settle in the colonizing country. Throughout Europe and the United States, transnational villages developed where people from a certain place abroad all settled together in another country. This increased the racial and ethnic diversity of the imperialistic countries while also establishing ethnic enclaves. However, feelings of nativism and cultural, ethnic, and racial superiority meant that there was little mixing of peoples. Foreigners were often kept apart and looked down on. However, after the passing of several generations, intermarriage has become more common than it once was and a degree of cultural amalgamation has occurred.
https://voxeu.org/article/politics-and-trade-evidence-age-imperialism

https://www.tamaqua.k12.pa.us/cms/lib07/PA01000119/Centricity/Domain/119/TheAgeofImperialism.pdf