Do published papers have to contain original work? Can I turn my MSc thesis into a paper and can the paper get published if it does not have original work?
The "mathematics" tag leads me to think that by "original work" you mean new theorems or at least new proofs of known theorems.  It's entirely possible to publish purely expository papers that do not contain original work in that sense.  Of course, such papers still have to make an intellectual contribution that is not already in the literature. That contribution might, for example,  be an improved arrangement of the material, highlighting connections that were not evident in earlier work.  Or it might be reformulating some known results in a way that facilitated applications.