Sorry, but this is just not true. TypeScript has almost nothing in common with C#. Yes they have both types, but TypeScript is a structural typed languages while C# is nominal typed language. They are as different as they can be.

I think you should look up what 'superset' means (specifically in the context of programming language design). It is not an opinion, but a simple and verifiable fact: TypeScript is a superset of JavaScript, with two exceptions where they added (ECMAScript) feature proposals before they became officially part of the ECMAScript standard. And both have made it into ECMAscript by now, so yes TypeScript is (again) a JavaScript superset.