Oh there are Dlls? And as a non-technical consumer I just know this do I? I know how to dig deep into my file system and copy+paste a dll file into software I can’t/don’t understand? How do I download and install a copy without Steam?

The premise of this hypothetical is Steam's servers going away. Ping me about this if and when it ever happens and I'll write you a tool where you can select the steamapi.dll you downloaded and have it copied to where your games need it. There's a fair chance you might not even need to because someone else will have made it before me.