When you're reading books about different cultures, it's pretty easy to stumble over references to other myth systems. In Anansi Boys, the mythology is overwhelmingly West Indian, and even more overwhelmingly Ashanti.
When the slaves were brought over from Africa, they brought their beliefs with them, and those mythologies exist to this day.
It's tremendously easy to make an error or miss a reference, just because you're not familiar with the myth system you're reading about.
If you've read the Anansi stories that Gaiman includes in Anansi Boys, you might recognize one that sounds an awful lot like a 'Brer Rabbit story, with the Tar Baby. Think about that for a moment... 'Brer Rabbit... 'Brer Fox.... It's the same myth system as Anansi, where all the minor gods are animals! But in the 'Brer Rabbit stories, Rabbit is the trickster, rather than Anansi. (Perhaps Rabbit was inserted by someone who didn't like spiders!)