a computer meant that the port was connected to a network card which was inserted into a slot dedicated for that very purpose in order for the user to be able to access the established network.

Now I am assuming that the same port on my computer is connected to some sort of network connection on the motherboard which allows me to connect to my router for more consistent connection and higher bit rates for streaming or podcasting etc.

So here is my question. For my buddy who has a Macbook Pro with no ethernet port he can use a USB-C to Gigabit adapter which allows him to connect an ethernet cable and do the same thing. What does a USB or USB-C port actually do on a computer? How does it access basically any and every function aspect that is available on the motherboard itself? Camera, Audio, Hard drive and in this case ethernet connections? I have several USB ports and I get it that we all just plug and play without really thinking about it, but understanding how a motherboard functions, it really is kind of amazing to think that a single port gives you access to pretty much every function your computer is capable of.

Could someone who gets this explain it to someone who still remembers that network cards were really these motherboard looking things with an ethernet port attached to it vs something that more resembles a a cpu or a ram chip.