Actually, D is a real thing: https://en.wikipedia.org/wiki/D_(programming_language)
And so is E: https://en.wikipedia.org/wiki/E_(programming_language)
And F (though it can be argued that it’s a subset of Fortran): https://en.wikipedia.org/wiki/F_(programming_language)
So, if you’re making a new language that’s supposed to replace C, call it G. The letters even look kind of similar.
I see you’re not familiar with the Esoteric Programming Languages Wiki: https://esolangs.org/wiki/Language_list
A person of culture, huh? Thanks a lot! I’ve been a longtime fan of the Esolangs wiki, in fact I dedicated a great deal of effort to prove that Numberwang is Turing-complete. I devised a method to translate any Brainfuck program into it, began writing a script to do so but lost interest before completing it.