At the lowest level (in terms of the operation of a computer), there is the hardware. Hardware includes everything that we can see and touch. Obviously, the hardware of a computer is important. However, most end users do not need to know the hardware components exactly.
But why not?
After all, different NICs are different in terms of how they operate. Different hard disk drives may use different interfaces (SATA vs. IDE). Different graphics cards also operate differently. Nonetheless, most people who purchase a computer from Dell or HP (or Lenovo and etc.) never have to worry about these differences.