There is no problem:
- You are only seeing the data usage for your computer and not all the others on your local network (LAN).
- Other computers on your local network need to know your computer’s IP address so they can communicate with it. In a similar way, web servers on the Internet need to know your IP address so they can send you the web pages or downloads you want to receive.
Printing and streaming or casting to your TV are good examples of why computers on a local network to be able to see each other other. You would want to be able to print to the printer or stream to the TV so those devices need to be visible to your computer.
The IP addresses you can see on your LAN will be local or private IP addresses, probably starting with 192.168.1. These addresses are different from the public IP address that is used for your Internet connection, e.g. mine is something like 27.252.226.63
Your wireless router has the job of protecting your local network from just anybody trying to access it. The router normally has a firewall enabled in it to check that any incoming communications match requests sent out from your computers. The router then routes the incoming response to the correct computer.