First by American I am sticking to just the United States of America. Last names are very mixed up as we are a land majorly comprised of Immigrants. Even the Native Americans are immigrants pushing out other tribes south in their own expansion and brought their dialects and naming sense to things. The Territory that the United States comprises of includes settled areas dominated by Spanish, English, French, Dutch, Swedish, Germans and others.
Throw in our period of slavery where we brought slaves from Africa over, renamed them into what ever their buyer wanted. Later immigrants came from Ireland, Eastern Europe, Mediterranean, Asia in various waves, so while it may sound like a word in the English language, but has a different meaning such as in the case of "Parent" which is an middle English and Old French family name.
Several immigrants especially in the 1800's through early 1900's got their name changed because it was unpronounceable or unspellable to whoever vetted them into the country, not by the immigrants choice.
Later 60's and 70's it became a thing to change your name to new one to show or birth the new you. Then there were the those who used cool sounding hopeful names for their children.