Capital supremacy vs labour supremacy is a false dichotomy.
Certainly maximizing capital returns involves structural slavery/desperation that disadvantages labour pool. But capital/property whether private or communal should have an ROI that justifies using the capital. Capital/oligarch supremacy also involves corrupting markets against any possibility of disrupting their extortion profits.
Labour supremacy might want to dispossess property owners for worker profit. Might want to just guarantee 9-5 employment for 45 years, without any concern for productivity or usefulness of their output, with ideally revenue sharing regardless of profit levels.
Humanist economics has main principle of abundance. Perfect, or at least as fair as possible, competition is path to abundance. Both oligarchy and labour protectionism of their supremacy, inherent right to keep doing same job forever or obtain ROI on doing the same thing forever, and influence on the State to ensure their protections and subsidies, promote scarcity, and higher profit per unit of output, no matter how it is split between capital and labour.
Abundance means more labour and probably more capital (also spent on workers) to produce more stuff. More total spent on labour is arguably more pro labour than higher pay per employee. More money available to buy more stuff promoting more abundance in other industries.
Actual wealth is measured in goods consumption, where more goods is more wealth. Everything else is just transfer/holding of money. General population welfare should be prioritized over the dichotomy of capital vs labour supremacy, because that is the genuine welfare of nation.
UBI is the obvious path/solution to escaping the dichotomy. The power to say no to work, automatically makes labour market fair. Market disruption that threatens your job has a weaker case of your desperation forcing you to agitate for your protections. The more you are "desperate/entused for work", the easier it is for your to adjust to the abundance of jobs that you do not have to compete with desperate people seeking them. Warmongering nationalist protections of jobs is not needed if it means cheaper stuff, and more UBI from diverting warmongering spending and destruction to more cash to citizens. So, UBI redistributes power from State, and their solicitations of discretionary supremacism, to the people. It still makes capital and labour much richer overall, but eliminates their vectors for corruption. It is impossible to consider human sustainability, if war and immediate survival are priorities in their/your mind.
UBI is also empowerment to use your time (and steady income as a source of capital) to disrupt and improve society and yourself.
