You've only looked at this superficially.

First commit of Kovid Goyal kitty in October 2016:

* https://github.com/kovidgoyal/kitty/tree/de072b3b423ad114cc4...

Hacker News post about the KiTTY fork of PuTTY in September 2011:

* https://news.ycombinator.com/item?id=2979382

And that's not the earliest for the latter.