Stories state that long ago, before the Faydh and the Chancels, a Wizard created the first Kenku. He had apparently admired his pet raven and used his abilities to gift his feathered friend with arms and hands and intelligence.
Whether by choice or by chance, the original Kenku could not speak. While this limited their ability to interact with the outside world, it did not keep them from communicating with their Master, who understood the speech of birds. Apparently the first Kenku was considered a success, as the Master obviously made more.
And so it may have continued for who knows how long, but the Kenku are as curious as they are craven and they began to resent the Master who refused to teach them to speak. Inevitably, they took matters into their own hands and broke into the Master’s study one day, intent on learning a spell that would give them the ability to speak, so they could leave and live their lives as the common folk do. However, they were no wizards and were easily caught. The Master, in a rage, cursed the Kenku, stripping them of their wings and granting them the ability to crudely mimic the sounds they heard, but to never be able to truly speak them. Then he cast them out.
The Kenku today live as scavengers, scrabbling for survival, gathering pretty treasures and gold and attempting to set themselves up as important lords and rulers. Many if not most turn to banditry and theft and no one trusts them, nor are they welcome in any civilized community.