C and C++ teach you what people think computers do under the hood. It's actually totally not necessary to start with them or anything, but learning them after learning Python/Java/C# smooths off the rough edges that learning high level languages leave on you. Programming is 80% figuring out how to use data structures to do what you want, and most high level languages either focus on data structures too much (Java, C#) or too little (Python, Game Maker, etc). When you have to work with data structures at a lower level, you gain a deeper understanding of how to best use them and why they're designed the way they are, and it stays with you when you go back to high level languages.