It helps for when you have a variable that's for numbers and you use it as a string or something else, it shouts an error. In other words, it protects you from yourself

No, it is slower than JS but it can be compiled to JS. The point of typescript is bringing static (or generally talking, predictable) types to variables, so that treating erroneously a number as a string should be more difficult. In a large codebase, it's easy to make mistakes and debugging is not instantaneous but it needs time. Typescript helps here. You write more code but it helps you out later

Typescript gives you better suggestions, red squiggles where you would get errors or bugs if you try to run it, more information about whatever it is you’re using that’s defined somewhere else, and some other neat stuff like project-wide renaming that works every time.