This ventures into speculation and so may be removed by the mods, if so I apologize. But I find that highly unlikely. The poem and song that was written by Frances Scott Key was penned in response to a specific battle, the Battle of Baltimore. Where the British bombarded Ft. McHenry for 25 hours. But the fort held and the British withdrew. In the morning "the dawn's early light," Key strained to see if he could see if the flag was still flying, if the fort still stood.

Each line is a distinct reference to that event. Of course we only sing the first verse anymore. But in respect to the full poem and the situation in which it was written, a prisoner of war writing in praise of is fellow Americans fighting the British to preserve their freedom, the brave can only mean those Americans fighting the British, not a reference to Native Americans.