Many Cubanos have obvious African blood. She was saying that Cruz and his children were of African descent in an effort to hurt him in the South where he is running well. Obvious racial slur; a generation ago, it would have been libel per se.
She could have been more obvious by showing them all on a porch, but she was trying to dodge criticism by being a bit subtle.
Monkey, and the more common ‘porch monkey’ are common racial designators.
Ever.
Seriously.
"Subtle" racist dog-whistling is inaudible to me.