The National Football League (NFL) began in 1920 as the “American Professional Football Association”. And just like the league name, a lot of NFL clubs began as something completely different.
The Arizona Cardinals started as the Morgan Athletic Club. The Los Angeles Rams began as the Cleveland Rams. What used to be the Houston Oilers later became the Tennessee Titans.
And with some NFL teams, they took on the name of their pro baseball counterpart. Back then, college football and Major League Baseball were really all anyone cared about in sports; unless you lived north of the border in Canada so apologies are extended there.