He owned them. He was legally able to free them, of which he freed 10. He could sell the slaves children or their husbands or their wives. He could decide if they would be punished or not punished for attempting escape. He could decide when a slave was to be put on their own time. You may not consider that ownership, but that kind of power normally does not come by renting.
Jefferson lived in the reality of his time.
And he died in heavy debt.
The reality of his situation just doesn’t support the narrative of the slaving owning rich entitled white guy the SJW’s are trying to paint.