@Caroline,
It is a good question, I think I might know but it's hard to put into words.
Words are just sound-packets we assemble to represent
something; in other words, what specific sounds are used doesn't have any correlation to reason or utility. They are - I believe - for the most part just
arbitrary. The word "Milk" has no intrinsic reference to the white liquid that words represents to me. It could just as well have been Tsi, Irre or Jokal.
It makes sense that as different languages evolved, there'd be no single pattern for such representations. Now, where languages overlap in their word-set due to 'bleed-over', that's another issue.
So yea, I could be way off here. But to me, it just makes perfect sense that there's no direct correlation: They're just representations.
Thanks