We have had ultra-rich people and major wealth inequality for most of American history. Rockefeller (1838-1937) amassed a fortune in the 1800s in excess of $400B inflation adjusted dollars. By most measures, he was the richest American of all time.
The second richest American of all time is up for debate but contenders include Andrew Carnegie (1835-1919), Cornelius Vanderbilt (1794-1877), Henry Ford (1863-1947), or Bill Gates (1955-present).
Wealth inequality has obviously grown over the past 50 years but it’s worth noting that wealth inequality in general is not a uniquely modern problem. It is also exaggerated by comparing to the 1970s, where wealth inequality was at a historical low point (see graph below)