Why was Rosaro's school established in the novel, Earthborn?

Rasaro's School, named after one of the ancient Heroines in an earlier book of the Homecoming Saga, is a teaching establishment created in the course of the story by Shedemai the Starmaster, as an answer to the divisive teachings of human priests. It is situated to be especially close to the poor Digger people's tunnels, and to encourage perches for the winged Sky people to have access alongside the humans.