Edit: I asked this question on the Italian Stack Exchange and got some rubbish comments, so I'm trying here instead.
The vast, vast majority of native Italian (i.e. not imported from another language) nouns and verbs end in vowels. It's very uncommon for native Italian nouns and verbs to stop at a consonant. Yet, when we look at Latin vocabulary, huge number of words end in hard consonants, e.g. diem, emptor, nauseam, rigor, nos, id, meus, and so on and so forth.
Italian is derived from Latin and is arguably closest to Latin among all the romance languages, but what happened to the consonant endings? How did the same population who a few centuries ago used to speak Latin with all its consonant-endings manage to lose not one or two but all of them in the derived language? It's as if such sounds never existed in this population, like the sound ZI doesn't naturally occur in Japanese, or the sound æ (as in English man or stand) doesn't naturally occur in German.
It's stranger in this case because Latin after all originated in Italy, not in a foreign country. It's intimately associated with Italy's history and culture. So what happened?