This depends heavily on the level of the thesis (Masters, Ph.D) and the educational system in which the institute issueing the degree sits.
Typically, at Master's level you need to demonstrate familiarity and competence in the execution of research. Ie, you need to show that you can understand and implement methods. However, the results may be unoriginal.
For a Ph.D, you need to do original research. This means that an original result needs to be published in the thesis. However, the interpretation of original may take many forms. As you note, it's almost impossible to publish an entirely new form of knowledge.