"Where is my “Hello World " ?”
I am not even sure what you are asking, the device log says its has sent a msg and that the next one is queued - have you not looked in the console for the data arriving? at no point in your code does it print you data to the log so it will never show up there. Your sending a msg via lorawan and hoping a TTN gateway receives it, if t does you will see the data arrive in the TTN console under the app and the devices too.
As you say your not sending plain text, the idea is to encode your data/values/bits and send as bytes (smallest number possible) that are then decoded the TTN backed - plain text in not the approach here. There are loads of threads on there re data encoding.
Have you set up both and application and device in the TTN console? I am thinking yes, just noticed the device is ABP, look at the console for data arriving.
Also you shared you keys etc, not advised.