She was a person. Or more accurately, several persons whose stories got conflated into one, then grafted onto the earlier goddess stuff.
The West Irish story I heard as a kid was that when Patrick built his first church he chose to make a point by building it on the sacred site of Brigid, where each year at the end of winter she would be honoured with lights, fire, music, poetry and the like. The first year, the locals climbed the hill and burned down the church. Didn't kill anyone, their Lady wouldn't have liked that, but the church was right where they normally built their bonfire. Patrick rebuilt. Next year, same. And the year after. Eventually he made a treaty with the local folk that they wouldn't keep burning down his church, and he in return would leave a space in his church for Brigid. Which is why Patrick churches are supposed to either have a joint dedication, or a chapel or window named for 'Saint Bridget'.
JoB has a good point with 'let me ease you in with minor modifications'. That happened a lot.