Anyone who identifies with their birth sex is cis.

Knowing your sex is not an identity, otherwise all trans people would be considered cisgendered people of their biological sex, in fact trans people would be considered even more "cis" than other people of their biological sex as they more acutely aware of their biological sex than the regular person due to being so unhappy about it. So unless you are willing to call Chaz Bono a cisgendered woman for aware enough their sex to able to be unhappy about it it would be hypocritical of you to misgender non-trans people with false gender identities just for knowing the same biological facts about their bodies as trans people do.

Also, if it had been true we all had this cisgender gender identity you claim we have, it's strange indeed that we would ask you stop misgendering us with this false cisgender identity. Had we indeed had this gender identity you claim we have we would have felt validated by it, like you, and love being called this gender identity, but it's the opposite. Either people should be taken seriously when they talk about their gender identities, regardless of trans status, or nobody should be taken seriously they talk about their gender identities, regardless of trans status. It seems to me though that you think only trans people should be believed and that's hypocritical to me.