Yes, that is apparently the only thing what's left... I knew the cable might be the issue, unfortunately, in this moment I can do nothing about it. And it's true - this cord does not originally belong to the Arduino. It's actually a cord from my laptop cooler. I think I just needed to hear this from experts since I wasn't absolutely certain that this type of cable may be unable to transport information.
Also yes, this IS a Chinese clone and I'm aware of the difference between CH340 and FTDI chips. Yet I believe this is not the source of the problem.
Anyway, thank you very much for your feedback guys, It's good to have people like you on this forum and I'll let you know about the results right when I purchase (hopefully) proper cable.