Either it is just 0s and 1s, in which case it's binary digits (digital) or it's not just 0s and 1s, in which case it's not binary digits (digital). If it's not just 0s and 1s (and therefore not digital), you are obviously going to need something other than a Digital to Analogue Converter because by definition, a DAC only converts digital (binary digits)! I can't see what is so difficult to understand here?
Either a USB cable has been appropriately designed to carry a USB signal or it hasn't. If it hasn't, then by definition it is either not a USB cable or it is a faulty USB cable! AmazonBasics USB cables (for example) have been appropriately designed to carry USB signals, are rarely faulty and do indeed carry USB signals perfectly adequately.
Yes, there are different protocols used to transfer digital audio, some generic digital data protocols and some specific to digital audio data. If a DAC is a USB DAC, then by definition it must be able to resolve binary digits from a USB signal, IE., It must be able to resolve binary digits from imperfect square waves. The same is true whatever other protocols the DAC has been designed to accept; SPDIF, AES/EBU or HDMI for example.
G