That’s funny. But the glass is not in a superposition, the answer to the question is. It’s a glass that contains water and is just sitting there observable by all probably sick of being subject to stupid questions that have no meaningful answer.

Yes. If the next action is to add it’s half full, if to remove it’s half empty. If nothing then it depends on the previous actions.

Exactly - or the next action. The question “is the glass half full or empty” is a false dichotomy, the answer is: it is impossible to know without further info.