Complex sentence: At the time of Cary's birth in 1780, the house served as the plantation residence of Cary's master John Bowry, and he was more likely was born in slave quarters adjoining the house.
Split into simpler sentences: At the time of Cary's birth in 1780, the house served as the plantation residence of Cary's master John Bowry. Cary was more likely born in slave quarters adjoining the house.