It's not just movie dialog. It's from the Bible.Gen 1:27So God created man in his own image, in the image of God created he him; male and female created he them.
Exactly what it means for man to be made in God's "image" is a question for religion or philosophy, not for language.
It does not mean that God imagined us. That is a different word. To be someone's "image" is to mean that there are similarities or semblances between the two things.
See definition 5 here. It even uses this very phrase as its example.
Student or Learner