For my extended thoughts on these issues see the books Mystical Journey from Jesus to Christ and African Origins Volume 2
Suffice for now to say that you may find odd contradictions when survivors write the history books and when the history is based on faith-based religion. Indeed you may see some adoptions in the orthodox world religions especially at the level of lower religious practice including myth and ritual. However, they have to denigrate what came before so as to elevate themselves and to help the process the adoptions from the previous religion are used to facilitate transitioning people from the previous to the present religion. Nevertheless you will not find adoption of the third level of religion, the mysticism, since that is a deviation from the orthodox ideal or religion based on historicity, literality and faith instead of a mystic movement towards self-discovery and union with the Divine.