Let's clarify some things. C# is a simple language, but I use it for many things. It does so much for my needs. Although I didn't do much with C++, I was a skilled C programmer for a while.
To answer your question, no. Learning C made it more difficult to learn C# because C# does not have the same practices that C is. C is not object-oriented. C# is, however, completely object-oriented. C# programmers are generally rated on their ability understand objects and abstract concepts like software engineering patterns. C# and C# are essentially identical except for their curly braces and names. C and C#, as in music, are two distinct notes. . .
Other languages I program in, such as Pascal and PL/I were not object-oriented. Assembly language programming was something I also did. It is very similar to C programming, but totally different from C#. C actually comes from B, which was a macro Assembly Language for the DEC PDP architecture (where UNIX first developed). Macros are a common feature of Assembly writers. I found C to be as easy to use as water to a duck to water. C# with objects drove my crazy, until I finally found it.
I tried my hand at C++. I tried C++, but it was not my forte. C++ is a different paradigm from C, so you shouldn't use it as a crutch.
C# and JAVA share some similarities. It helped me to know JAVA before I knew C#.