The Rambam (9:13) is not necessarily referring to all foods that are edible raw. The Mishnah Berurah (318 shaar hatziyun 114) says that the Rambam means something that does not undergo any improvement through bishul, whereas fruits and vegetables which can be eaten raw but also improve with bishul does have a prohibition of bishul d'oraissa. However, Hagahos R' Akiva Eiger (254:4) says foods that are edible raw are only asur miderabanan.