Just my personal opinion:
- Small minority of people will always call it a ripoff as long as there is any similarity at all, even just for being in the same genre. I wouldn't worry about that.
- If you strictly remake the original game with different assets and add nothing new to the gameplay or story, but also promininetly give credit to the original, IMO that's a clone and there's nothing ethically wrong about it (see games like OpenTTD, Remnants of the Precursors and countless other tributes to cult classic games)
- If you do the above, but without giving credit, that's where I would draw the line personaly, and that's when I think your game could get some bad rep (but as you said, you're still not in any danger legaly. (cough)not-a-legal-advice(cough).
- If you take inspiration in the original game but make some substantial changes to the mechanics or story, IMO giving credit is totally optional (how many people call Minecraft a ripoff of Inifiniminer?).
Legaly speaking, reusing assets is obviously a big no-no, and I believe there are also some cases where copying the UI can get you in trouble even if the assets aren't exactly 1:1. But I'm not a lawyer.
“Good artists borrow, great artists steal.”
- attributed to Pablo Picasso