The problem is that your web server is bound only to the loopback address 127.0.0.1. You need to either bind it to the actual network interface or, more simply, bind it to all addresses (usually by specifying 0.0.0.0) and it will then be accessible by all other hosts with a route to your Pi.

You can see which ports and IPs your host is listening on with netstat -lnt or ss -lnt.

Your netstat output shows you the problem:

tcp        0      0 127.0.0.1:8000          0.0.0.0:*               LISTEN      743/python

Specifically, 127.0.0.1:8000 shows that your web server is bound only to the loopback address 127.0.0.1. You need to either bind it to the actual network interface or, more simply, bind it to all addresses (usually by specifying 0.0.0.0) and it will then be accessible by all other hosts with a route to your Pi.