Why is this the answer?

The answer is riddle because this is a very clever puzzle that describes itself. Think about what a riddle is. A riddle is a question or a statement that is phrased in a sneaky way and needs a lot of careful thought to be answered. This clever little puzzle is talking about the secret "key" you need to unlock its meaning, and that key is not something you can hold in your hand. Let's look at the first part of the riddle: "To unravel me you need a simple key." To 'unravel' something means to figure it out, like untangling a messy ball of string. When you solve any riddle, you need a special key of understanding to figure out the tricky words and the hidden meaning behind them. That mental key is the one correct word or idea that finally makes the riddle's picture clear in your head. The next part gives an even bigger clue when it says, "no key that was made by locksmith's hand." A locksmith makes keys out of shiny metal that open real doors and real locks. The riddle tells us that the key to solving it is not a physical object. It means the answer is not something you can find on the floor or a tool you can touch. It has to be an idea or a word, which helps you narrow down all the possibilities. Finally, the riddle wraps it all up by saying, "But a key that only I will understand." When you figure out a riddle, the correct answer *is* the simple key that unlocks every single clue. The riddle is talking about its own nature. It is a puzzle that you solve by finding the one word that fits all the secret descriptions. The only word that perfectly describes needing a simple, non-physical key to be 'unraveled' is the word 'riddle.' All the words in the riddle are pointing right back to the word "riddle" itself. That is why this riddle is so special and fun to solve.