Pt 2 Howyouducan's Kenku Lore
Kenku are said to be a splintered race, with many clans or flocks living apart, and having entirely different traditions and knowledge pools. There are also many kenku who live alone or in small groups in cities across Faerun.
Their history goes like this:
There are two dieties, an elemental goddess of air, Akadi; and Quorlinn, a trickster folk hero who supposedly helped create the kenku race (with the aid of an unknown "sky diety" who refused to take credit, wink wink).
Quorlinn, long ago in his youth, had been considered a failed god, the experimental creation of An Unknown Sky Diety (Wink Wink). Quorlinn, appearing as a figure dressed in plain clothes and a pointed black mask, was a strange god. He was not very powerful but cunning, quick, mischievous and resourceful. In these days he had been desperate to prove himself, and often went on escapades that brought useful things to the table but which also cost him some close calls and tail feathers; so, usual trickster folk hero shenanigans.
Eventually, Quorlinn's antics finally got through to this sky god, who relented to give him a gift, and thus created a race in Quorlinn's own image.
Quorlinn, however, was not thrilled with this outcome. Although he had earned his place as a diety, he did not want to be solely responsible for an entire race. He became a teacher to this race, and imbued them with an impeccable memory and the gift of mimicry, not unlike regular corvids, so that kenku may be able to fend for themselves.
Start of Cornix Accursio's backstory, non-official lore:
Some hundreds of years later, kenku, for ultimately unknown reasons, could not create beyond what their own memory provided, forcing them to rely on mimicry. This at the time was true of kenku everywhere. At this point, one ordinary clan of kenku once again beared witness to Akadi and Quorlinn's awkward situationship, although this time it was by the brunt of a dispute.
You see, the kenku worshipped both dieties, however the argument was of who was responsible for taking credit. Akadi did create the kenku and had since accepted many gifts from them, however Quorlinn considered himself their patron, having looked after the kenku since time immemorial.
There is a much longer story to be had here; but for now, the outcome was this: the clan became split in three.
One part was neutral in their loyalties. They regained the gift of free wonton creativity, abolishing the limits of memory, and they spread across Faerun very successfully. This is the playable race in 5e.
One part sided with Akadi, and they too had their disability erased, and also grew wings like the aarakocra, becoming a very rare case of flighted kenku; and they moved into some abandoned floating temples of the ancient aearee.
One part was given neither. These kenku sided entirely with Quorlinn, and continue to this day to carry what they say is an old curse, forcing them to rely on their racial gifts of memory, mimicry and cunning. Due to conflict with the winged and neutral kenku, this part of the clan fled to Shadowfell to build a village entirely inhabited by flightless and cursed kenku. This is the clan Cornix hails from.