How can dev implement switch race but not being able to get original race heroes?

For example, if I am human and want to switch to dwarf I am unable to get Nora (which is a big + to have if you use dwarf units) and still have Viron (which is useful as human race).

Nora isn't in the game currently. And the free heroes are baseline regardless of your race. I have been asking for sometime for us to have he ability to choose from a selection of heroes at each tier instead of getting mostly human based heroes.