Nooooo i'm not ready for my comfort manga to end...
Also "I caught you", isn't "caught" supposed to be "taught"?
"caught" makes sense, since Jingujii went off alone planning to sacrifice his own life and mind to finish the task. Tachibana caught up so they can face the challenge together.
This situation is "The demon lord is just a baby, not an actively plotting mastermind behind everything". It throws a wrench into the mix, but the basic formula that they've been told, "Demon Lord = root cause of everything" can still be thought of as potentially applicable, where as I noted above the baby is still actively doing something just by existing; just unfortunately happens to be an infant and doesn't consciously know it's doing it. Or at least those are reasonable assumptions to make, if one doesn't stop to think about the details I noted above.
A conjecture on the Demon Lord's original from what the story told so far:
The creator god + goddess who were slumbering as the land, whom left the reign of world to the twelve goddesses, the goddess' squabble and conflict escalates to wars that kills so many people, with nuke level weaponry left whole country in ruins.
The creator goddess, disappointed, created the 13th offspring, whose follower/officers appear to have similar immortality of the 12 goddesses, (can only be beaten by breaking their core, even then they just become a smaller version of themself, can grow back over time.) Their technique is mostly focused around take over a power source and warp it to their own use, (ie, Vizd, Meepon, prison island fireball, Mori, Rin, Shishii's loyalty.)
The goal is probably to stop the warring goddesses who were about to destroy the world.
Though i wonder about the goddess covenant's decision to kill the "Demon Lord", whom was an unknown entity that suddenly put a stop to their power, apparently Love wasn't invited to that meeting, and she summoned her heroes last, to catch up with what all other goddesses were already competing.