In a nutshell: OpenWRT existed. They kinda sorta pretty much stopped doing anything. LEDE sprang up as a fork, with several of the OpenWRT folks. Then they all decided to work together and joined back up. Now it's anybody's guess what will happen next, if anything, as nothing has really happened since.

That is not true in my experience, the LEDE site is quite active, spewing out builds very frequently, even fixing KRACK almost immediately. Don't know what you consider as "nothing has really happened"

OpenWRT is dying, but LEDE is alive and kicking hard.

The mailing lists mention LEDE will merge back to the OpenWRT branding, but that was months ago, and the OpenWRT site is funky.