As silent film was on the decline, Chaplin decided to hold on to its form despite the massively popular appeal of talkies. Yet despite the fact that he was operating in what was becoming commonly considered an antiquated format, this film was received as his masterpiece and shows his success as a truly visual filmmaker. This film sets Chaplin apart from Keaton as just a stuntman. City Lights shows Chaplin's capacity as a dramatic storyteller as well. His focus is clearly on eliciting emotion and creating a connection to the characters within his story. You are not just meant to laugh at the individuals suffering onstage but rather feel their suffering as well. And he earns this drama through the time he gives to each beat and moment in this story. The gag doesn't just end and transition into another gag, the Tramp and the Blind girl are given a reaction shot here and there to really emphasize the beats and the way they are taking in the effect of the actions that just occurred. You can see it in the performances as well. The Blind girl is nuanced in her expressions and while the film is stagey in how it is shot, meaning there are mostly straight on or contextualizing Mediums, close ups and wides it focuses on the story and actors rather than the gimmick or gag occurring. The edits punch into close ups or cross cut between close ups to really make sure you understand the character's emotional state rather than using those cuts to time a goofy reaction shot to a gimmick.
City Lights really shows the contribution of film to the humanity of our civilization. Chaplin was making films that were universal and would last forever in their stories and characters.