Caveman talk

Aside from metaphysical meanings ascribed to the letters in the alphabet, I've been wondering what some of the first meanings were in caveman times. I'm guessing vowels were prime, so a few speculations. The short a sound might've been expressed as satisfaction, like after drinking a cold beer on a hot day, or after an orgasm: "Aaaaah, that was good." The long a sound when one was insulted, like "Aaa, WTF man." The o sound when one was perplexed: "Ooo, really?" The long e sound when one was startled and frightened: "Eeee, did you see that dinosaur?" The short e sound as in "eh, no big." And so on.