I did have to turn to my own copy of the script to get a better sense of Leia already thinking Wicket might be an ally (and then have to admit remembering certain smugly barbed comments from others about "the Rebels getting the Ewoks to sacrifice themselves," to say nothing of the learned proclamations the Death Star's glowing vapour would fall on the forest moon after exploding and sear its surface). So far as "invented to be merchandise" goes, there was a comment in the "Making of Return of the Jedi" book published for its thirtieth anniversary about preproduction having trouble with "small, furry beings" when it was decided to just "lean into the cuteness," if also an unfortunate amount of insinuations most people in the production were already disdainful of the Ewoks ever afterwards. The online unpleasantness a decade afterwards didn't appeal to me at all (to say nothing of what targets it fixed on afterwards), but I'll admit to liking in the 1990s how the Return of the Jedi novelization developed the characters of the Ewoks (even if nowadays I'm not so enthused over how it seemed to have "Vader's return to the good side" come out of just about nowhere).