This is the Torah: when a man dies in a tent, all who come into the tent and all that is in the tent shall be unclean seven days.
Torah Temimah: Bechoros 45a — Extra limbs of a woman do not convey tent-impurity, as it is said “This is the Torah: a man who dies in a tent” — something that is equal in every person.
English: Extra limbs of a woman do not convey tent-impurity, as it is said “This is the Torah: a man who dies in a tent” — something that is equal in every person.
Restriction to features common to all persons.
Only limbs that are standard to every human being convey tent-impurity; anomalous extra limbs do not.