i dreamed that my uncle was a crab despite that i still greeted him normally. When i went to tell my grandmother that my uncle was a crab she dismissed it and told me it was time to wake up
The dream seems to be symbolic and metaphorical in nature. Crabs can represent feelings of vulnerability and defensiveness, or it could represent that the uncle has traits such as being hard-shell, or perhaps he is prone to "pinch" or criticize with his words.
Your reaction in the dream, greeting him normally, indicates that despite his unusual form, you still accept and acknowledge him.
However, when you tell your grandmother, she dismisses your observation and asks you to wake up, which may suggest that the dream is urging you to move on from any grievances or issues you may have with your uncle and not dwell on them too much.
Overall, the dream may be reminding you to focus on accepting others for who they are, regardless of any quirks or quirks that they may have.