It's clear that this is the author's first book because there was a lot of telling-not-showing of the main character's thoughts and feelings. It was so frequent it was getting a little annoying. This was a particularly bad decision for the personal revelation near the end: it felt like the author was spoon-feeding the reader when they could already chew (that is, figure it out with minimal explicit sentences based on established details). 

The racism/colorism/colonialist inferiority complex elements could be slightly more subtle. It's repeated so often and explicitly that if one is reading much of the book in one sitting, it feels like the writing is hammering the reader upon the head with "prejudiced White people-equivalent colonialists of fantasy-Africa are using religion and colorism as a tool to control the local population, sow division, and make them feel inferior so they obey the colonizers". I don't object to portraying this idea in middle-grade other-world fantasy fiction in principle, nor, for the most part, in execution. After all, I've enjoyed many books with similar themes. Rather, I think it would be better if the book had about two fewer sentences about it.