In every cry of every man, In every Infant's cry of fear, In every voice, in every ban, The mind-forg'd manacles I hear (5-8)
The anaphora here ("In every"… "In every"… "In every") paints a bleak picture. Everybody is enslaved by "mind-forg'd manacles," which is to say nobody is innocent anywhere. They are all enslaved to something: experience, pain, sorrow—you name it.
How the Chimney-sweeper's cry (9)
Chimney sweeps were children. Because of their job, they were very dirty, or "black," which is associated with everything but innocence. Yeah, sure, they're not described as covered in soot, but come on, we get the message, right?
And the hapless Soldier's sigh Runs in blood down Palace walls. (11-12)
Blood on the walls might as well read "blood on their hands." The Palace is, by no means, innocent of bloodshed in the world of "London."
But most thro' midnight streets I hear How the youthful Harlot's curse (13-14)
The word "youthful" is important here. We expect youth to be associated with innocence, but here it is clear that the youthful harlot is part of the world of dangerous, sexual experience and (as we soon learn) disease.