I've no idea what it refers to either, but pigeon owners take great pleasure and enjoyment breeding and training them. Perhaps that's what they refer to regarding how they have impacted the lives of humans?

I cannot speak for pigeons as I am a human, but if I was fed, watered, had a comfortable home, often with radio or TV, high quality medical care, and in return I fly a few times a week? Sign me up!

They are breed for the purpose of flight (or sometimes looks). They cannot be "left alone" as they're not quite the same as feral pigeons.

There is absolutely no shame in keeping pigeons, caring for them, and racing them.