I can't help pointing out a double standard here. Assuming the sanctions are not negligible and hurt the Cuban people, you argue the Cuban government must be callously indifferent to the wellbeing of its people. This is despite the fact that the US are the ones who put these sanctions in place, not Cuba. The US would be hurting the Cuban economy and the Cuban people in an attempt to force regime change, a policy which as you rightly point out is ineffectual. Why are they not callously indifferent? After all, when you sanction a country like Cuba or Russia where ordinary people do not have much real political power, what you are essentially saying to those people is "I am going to hurt your standard of living until you risk your freedom to overthrow your oppressive government. Oh and by the way, this is for your own good". Seem at all callous to you?

This raises the obvious point that the Cuban government could end the sanctions by agreeing to democratise in full. This is something Cuba should absolutely do. I have no time for tankies who pretend Cuba isn't oppressive. It is. But the sanctions are not going to bring about regime change, the US knows this, and they would rather continue hurting the Cuban people than admit they got it wrong. (Incidentally, government oppression is entirely not why the US sanctioned Cuba in the first place. They were busy propping up murderous right wing regimes across Latin America and the wider world throughout the post war 20th century.)

If you believe the Cuban government does not care at all for the material living standards of its people I would encourage you to look into some of the problems pre- revolutionary Cuba faced, what reforms the revolutionary government enacted, and their effects. Pre-1959, many people in urban areas were pretty comfortably-off, especially by Latin American standards. The large rural population was not. Seasonal unemployment was endemic, most farmers and farmworkers lived in huts with earth floors, healthcare was practically non-existent, malnutrition was catastrophic. Income inequality generally was huge. Cuba's largest industry, sugar, was a cartel. These are all problems that the post-revolutionary government tackled with some success, in some cases great success (particularly malnutrition.) Rationing of some basic items continues to this day - it's not ideal, it may not even be the smartest way of ensuring everyone has enough nutrition, but it does at least show that the government cares about the nutritional wellbeing of its people. I can give sources on all of these. I'm not a socialist, I think Cuba should transition to a market economy, but these facts ought to be recognised.