It's sometimes hard to say because George Lucas retcons George Lucas so often you can never really tell what he intended anymore.
Lucas has asserted that all of Star Wars is for kids
"The movies are for children but they don't want to admit that. In the first film they absolutely hated R2 and C3-PO. In the second film they didn't like Yoda and in the third one they hated the Ewoks... and now Jar Jar is getting accused of the same thing."
I mean you're calling out marketing to kids some cuddly little savages. If you step back and think about it, virtually nothing about the Star Wars universe is really kid friendly. Han Solo kills a bounty hunter in cold blood. Luke's aunt and uncle are massacred and he has to cremate their bodies (I had to explain that one to my kids). Ironically, my kids had few issues with the Ewoks because they were, indeed, cute.
What I don't see is any attempt at making them a pure marketing ploy at the time. I mean, compare the Ewoks to Jar Jar Binks (who was a walking, talking marketing tool). Here's George talking about ROTJ
At about 0:46 he talks about the Ewoks and he, rather blithely, states
I took the Wookies and cut 'em in half
Lucas originally made Endor for the Wookiees, but wanted a primitive culture to overthrow the Empire (Wookiees could, you know, fix starships). So you've got to invent a new race here. But the video makes it sound like pre-retcon Lucas was taking a pragmatic step and just took one furry race, made them shorter, and called it another furry race. I doubt very much that marketing wasn't far from his mind(Lucas is a master at marketing toys), but, as you note, the troubling aspects of their society make them far from perfect kid subject matter. All of the kid specific stuff that came afterwards just avoided the subject (most notably the two Ewoks live action made-for-TV movies, neither of which depicted them as pure savages).
I mean, who can't forgive the whole "we eat humans" thing after seeing this face?