Funny cartoon! For the young folks, that penultimate frame is from an old folk song; I don’t know if it has a racist history or not. If may have originated with IRISH slaves, guessing from the melody (yes, the Irish were enslaved by the English also).
The tale of the Irish slaves is rooted in a false conflation of
indentured servitude and chattel slavery. These are not the same.
Indentured servitude was a form of bonded labour, whereby a migrant
agreed to work for a set period of time (between two and seven years)
and in return the cost of the voyage across the Atlantic was covered.
Indentured servitude was a colonial innovation that enabled many to
emigrate to the New World while providing a cheap and white labour force
for planters and merchants to exploit.