In the US a CS student entering a doctoral program with only a bachelors seldom actually starts out with their dissertation advisor. There is plenty of time to meet people, see what they do, and impress them. The program is normally heavy on coursework initially. You might wait until your third year or so to actually wind up with the professor who will guide you.
This can be different in other fields and certainly is in other countries, but I wouldn't be a bit concerned about the situation.
The other professors aren't replying because it is too early for them to even think of considering you. Your situation is completely normal here.
The required classwork can be quite extensive since most programs require that you obtain a broad education in your field as well as a deep knowledge of some part of it. Almost all programs have comprehensive exams (maybe three or four) that must be passed before you get too deep into specific dissertation research. These assure the broad knowledge expected of any PhD.
Also, most students in such programs have either a TA or an RA that supports them financially in return for various activities that also prepare you for a career in academia (primarily). And such students don't pay fees, though they have living expenses, of course. But that would be the case anyway.