Welcome!
I had no recollection there was a Hanna Barbera cartoon but the title The Godzilla Power Hour does ring a vague bell. Being a bit older my introduction was an afterschool monster movie broadcast on a local US crossborder station while the Showa films were still deemed ok for a young afternoon television audience.
Your experience reflects what I think is the great thing about Legendary Entertainment and Apple bringing the Monsterverse to television. With AppleTV’s reputation for high quality science fiction, it’s encouraging audiences and demographics to give the show a chance who might otherwise pass on anything from the longstanding broader Godzilla franchise.
You may not be familiar with the truly awful US film Godzilla (1998). The general view is that it was so bad and so disrespectful of the IP kaiju that had been licensed from Toho — the producer of the Japanese films and IP owner — that Toho became very strict in its licensing of the IP from then on, with covenants about how Godzilla and other Toho creations could be used narratively. Legendary Entertainment has been using the licensed kaiju carefully in its movies and shows, but has also been adding new creatures to provide original elements.
M:LOM seems to be performing as well in Japan as well as elsewhere. Flix Patrol hs the show ranked number one in AppleTV in Japan every week since the season premiere. There’s an earlier post with feature article from the Japan Times that you might like to check out.