A mannequin has the shape of a person but no life of its own, so it is read as feeling like a display rather than yourself. It can point to going through the motions or being judged on looks.
Does the traditional reading fit your dream, or did it mean something else to you?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.