Dickens' humanitarianism lies in that the rulers should be kind to the people (Darnay's image), and the people should be tolerant, repay their grievances with virtue, and build a harmonious society.
In addition, I personally think that the most prominent feature of the novel is the combination of history and fiction. Twin cities refer to London, England and Paris, France. At that time, the Great Revolution had broken out in Paris, and it was shrouded in disorderly tyranny. Dickens also wanted to express a historic idea that Britain is now in a precarious situation. If there is no improvement, similar riots will always break out, and I hope the rulers will adjust their strategies. This should be regarded as a feature of literary thought.