The Impact of Urban Setting on Isolation

In the following excerpt from a novel, the setting deeply influences the protagonist's emotional landscape and decisions:

"The city was a labyrinth of concrete and chaos, where the sun rarely penetrated the gray skies. Rain dripped incessantly from rusted gutters, creating pools of murky water that reflected the distant, flickering neon lights. The air was thick with the scent of wet asphalt and faint hints of jasmine from a lone balcony flower, fighting to survive amid the urban sprawl. Each night, the streets buzzed with the hurried footsteps of strangers, their faces hidden in the shadows, as if carrying their own stories tightly sealed."

Given this passage, what aspect of the setting most significantly contributes to the protagonist's feelings of isolation?