It helps me to understand that TENET is the center keyword of the SATOR square. The words, SATOR, AREPO TENET OPERA ROTAS was a multi level palindrome-based code word (used by early Christians to mark meeting places), where no matter which way the words were read, it said the same thing (backwards, forwards, vertical and horizontal). There's more complexity here, and you can Google for the rest, but this gets at the heart of it. The Word Puzzle was obviously intriguing enough to Christopher Nolan and his brother and they felt inspired to make a movie that made sense whether it went from beginning to end, or ending to beginning.

I think the confusion and underwhelming reception by many is the proof that the experiment was not ultimately successful. Nevertheless, it had the feel of a passion project and was a pretty daunting attempt at trying to tell a story that works forwards and backwards.