Should Neuro-sama be in the game? Does the game have to be about her to win this game jam?

Nope, submitted games do not need to be themed around Neuro-sama at all.

Most of them will probably end up being, because it’s the Neuro jam after all, but if it’s not then there is no problem.

See for example this game from last year’s jam: https://itch.io/jam/neurosama-birthday-game-jam/rate/2445255