There's never been just one person or a group of people who have had the job of sitting down and coming up with words for us to use. In most cases it's impossible to figure out just who invented a word!
Words have to become very popular before they enter our language. Often, by the time they become that popular, we've forgotten where they started. Words are made up because we need ways to describe things. If an object or an idea doesn't have a word to go with it, someone will make one up.
Words can be based on the sounds some things make. They can also come to us from different languages that already have a word that describes something. The English word "house" comes from the German word "haus". They both sound almost the same! William Shakespeare gets credit for inventing some English words. Some words like "eyeball" don't appear anywhere before he wrote them into his plays or poems. He may have heard "eyeball" somewhere else, but still the credit is given to him because he was the first to write it down.
Our language is always changing and new words are always being created to describe new things. Words like "email" and "ringtone" are pretty new to the English language because those things didn't exist until recently.
Onomatopoeia "Onomatopoeia" is a pretty weird looking word. Most people pronounce it like "on-oh-ma-toe-pee-uh." It comes to the English language from Greek words that mean "name" and "I make." We use it to describe words that are created from the sounds things make. Words like "croak" and "bark" exist because they remind us of the sounds frogs and dogs make! Words like "jingle" remind us of bells. How many things that make noise can you think of? What words are used to describe those things? Do they sound like the object or sound they describe? Here are some examples of onomatopoeia to think about: crunch, zip, cuckoo, meow, splat, bam, boom, crinkle, splash, and hiccup!