1a) I agree we need larger studies to know whether competition in commerce as as powerful as fans of capitalism say it is. But the Covid stimulous isn't really analogous because it was so spotty.
1b) I'm a socialist. I don't think UBI is the full solution. It only raises the bottom. But since the bottom is disproportionately female and of color, it would disproportionately help women and poc.
2) Many groups are poor for unique reasons under capitalism—if you focus on race alone, that includes Appalachian Americans, who have suffered from generational poverty for centuries. Even if you take a race reductionist approach and exclude all white people, that leaves American Indians who are poorer than black people and Hispanic people who are almost as poor as black people. Why not cut to the chase and end poverty for everyone?