https://en.wikipedia.org/wiki/Grand_Union_Flag
https://en.wikipedia.org/wiki/Flag_of_the_United_States
Ross was merely one of several flag makers in Philadelphia who is historically documented to have made the earlier Grand Union Flag for the Continental Army, along with many other ships' colors, banners, and flags which were advertised in local newspapers.
Francis Hopkinson designed the first official American flag. https://en.wikipedia.org/wiki/Francis_Hopkinson
Mary Young Pickersgill (1776–1857) made the 1st flag of 15 stars and stripes in 1813, begun at her house and finished on the floor of a nearby brewery, along with a smaller flag then seen by Francis Scott Key on Fort McHenry. It is thought that Betsy Ross' only contribution to the flag design was to change the 6-pointed stars to the easier 5-pointed star.