The “suffering servant songs” are found in Isaiah 42:1–4; Isaiah 49:1–6; Isaiah 50:4–7; and Isaiah 52:13–53:12. All these songs describe someone who brings hope and salvation. In their original context, they describe a nation rather than an individual. This is because the society was collectivistic, with an emphasis on family and groups, as opposed to our individualistic society with an emphasis on the person. These are traits of a whole group of people. It wasn’t until the Christians read back through this material that they picked it up and applied it to a single person. The application of the suffering servant songs to Jesus is probably the oldest theology in the New Testament.
Everywhere these suffering servant songs appear, they interrupt the narrative flow of the surrounding text. If removed, the flow is restored. It’s almost as if they were not native to the text and someone just stuck them in at random places.