I wouldn't say sentient and organic have anything to do with each other in Mario anyway. The question is more of what the minimum requirement is for something to be "alive," as examples of all combinations exist.
Clearly alive but probably not sentient: M&L:SS Goombas, Yoob, Little Mousers
Clearly sentient but would make sense to be inorganic: Yakkey, Monsieur Broque, some Thwomps
Clearly organic and clearly sentient: Lubba, E. Gadd, Wario
Clearly inorganic and clearly non-sentient: Coin, hammer, boot