What you are referring to as the World Wide Web (WWW) is simply the network ran by ICANN or IANA, which was an offshoot of the US Defence program's ARPANET project.

A simple network that one can understand is that of a mobile connected to the PC via a PC Connectivity Cable, such as a USB cable.

It could then be configured to connect via the MTP protocol, and any computer that recognizes that protocol will be able to access the files in the device as per the protocol.

A next step would be a wired network (USB Tethering or Reverse Tethering), or more commonly understood, a wireless radio network such as Bluetooth or Wi-Fi. In these connections, there is a central device acting as the AP (access point), also commonly known as a Hotspot. These connections allow you to access internet traffic via the gateway device, which would be the one hosting the Hotspot.

Of course, the traffic would be End-to-End encrypted via X.509 format TLS certificates between the user and the endpoint (remote server), otherwise Wi-Fi hotspots would not be popular. But if you wanted to access files via that network, it should be configured separately, with the host providing visibility for any other devices in the network you want to access. Sure, you could be part of multiple networks at once.

So, every network is like this, but may have different topologies.

So we could only form a "global internet" by connecting to a standard network. The WWW was thus the standard by which countries established network routers to form local Internet Service Providers (ISP).

While these networks can only be used

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