These are, of course, Hob, having lived for several centuries and tried his hand at various occupations and trades.
Hob is distressed, remembering that while he owned the fleet of ships he was a slave trader and brought slaves to America. The English owned all the ships that brought the slaves to America. They would sell trade the slaves to the colonies for cotton and molasses, which they would bring to England. They would use the profits from the sales to purchase more slave.
When England made slave trading illegal and they were at risk of being boarded while in transit or if there was bad weather they would sometimes dump their cargo. The slaves were all chained together and so when one went overboard they would all quickly follow.
Hob is still haunted by nightmares of this.
Gwen doesn’t know that Hob is over 600 years old and was responsible for some of these actions. While she thinks that some things can just be forgotten, Hob is unable to do that.
This is one of the slaves from Hob’s memory.
He appears in Sandman # 73, on page 6, in panel 4.