True, but over Jefferson’s life time he owned over 600 slaves. He freed 10 of them. Five while alive and five in his will after his death. An aside. eight of the freed slaves were blood related to Sally Hemming. Without those slaves, could Jefferson have been Jefferson.
One of Sally's children was named Madison Hemings. In 1870 he was living in Ohio. The census taker wrote in the margin next to his name: "This man is the son of Thomas Jefferson." Obviously that's what Madison had told him.