An examination of modern languages does reveal a few structural commonalities, which may well point to how meanings were assigned to common early human sounds. Here are two examples . . .
GR words a large number of words starting with the letters gr- relate to nature. English examples include such words as grow, grass, green, and so forth. This suggests that the gr- noise may have been used by early humans to relate to the natural physical world around them.
GL words equally there are many words starting with the letters gl- that relate to light in some way. English examples would be such words as glint, glow, gleam, and so forth. Perhaps the mouth-noise of that word opening is also very ancient and related to daytime light in various ways.