The action matters, but so does who makes decisions, who is watching, how novel the situation is, whether it feels taboo, emotionally intimate, anonymous or intensely focused on one person. Two fantasies that look nearly identical from the outside may mean completely different things to the people imagining them.
That does not give us permission to assign a hidden psychological meaning to every fantasy. Science cannot reliably look at one person’s scenario and say, “This detail definitely means X.”
But we can become more precise observers of our own patterns. Someone may notice that the characters in their fantasies constantly change while one feature remains: they are always the centre of undivided attention. Someone else may notice that very different scenarios all share the experience of no longer having to make decisions.
That is not a universal theory. It is a person noticing a recurring pattern in their own erotic imagination.
Fantasy then becomes interesting material for curiosity rather than self-diagnosis. We do not necessarily need to discover a hidden truth about our personality. Sometimes it is enough to notice which kind of experience the brain repeatedly chooses as erotically interesting.