Jeremiah is shocked by this. He recoils from this task. He has a good reason for this: he is still very young, and so inexperienced that undoubtedly no one will listen to him. At that time, young people (younger than 30 years) were not taken seriously. And Jeremiah was probably younger than twenty. In the Bible you often see that people shy away when they are called by God. A similar person is Moses (Exodus 3:1–22).
6 Then I said, “Ah, Lord GOD! Behold, I do not know how to speak, for I am only a youth.”