The barriers are so complex, and perhaps different for each of those groups. While we don't like to think about it, some of those barriers are unconscious or conscious bias, so we have to shift the culture, shift cultural attitudes towards certain groups.
We also need to create more inviting spaces for certain groups, for example, for indigenous peoples. Part of not only getting indigenous peoples into leadership positions but keeping them there is creating spaces that speak to their cultural traditions.
It's a question, then, of changing attitudes, creating spaces and, going back to education, of making sure that the education environment is also inviting and speaks to the realities of specific groups; for example, when we're teaching certain subjects in schools, making sure that we're including either literature or examples in math that speak to different groups, so that people can see themselves in the educational system.