English language

Why in the world do languages have words that are spelled the exact same but depending on how you say them they mean different things. Please life is already confusing enough why add one more thing...For example invalid, look it up in the dictionary and use the audio function. I think it is dumb. I have been informed by Mookie (how the h*** she knows this is beyond me) that they are called heteronyms. There are so many heteronyms, who would have thunk. I am lucky i know what an adverb, noun and pronoun are, not to mention an adjective.