It's exactly a (forced as a political matter) economic isolation situation. North Korea is another politically isolated economy. I don't think they're doing very well either.

Trade helps poorer nations more than it helps richer nations, but it helps both.

There are billions of people living under worse regimes than Cuba, yet only it and a handful of other nations have been on the receiving end of US sanctions. This was devastating to its economy (prior to the revolution it was of course Cuba's biggest trading partner).

There is no justification for the embargo. It was Cold War aggression, pure and simple, now sustained for the last decades purely because of electoral reasons.

I completely agree politically, assuming Cuba is no longer willing to host missiles or other non-defensive military apparatus from an adversarial nation.

Like Turkey hosted our missiles to hit Russia? No, sorry, I forgot, that's okay because we are good and they are bad.