Generally people aren't looking for immortality in the "evil magic curse" sense. They want immortality in the sense of being able to preserve your body and your mind in your prime indefinitely. A magic curse where you suffer forever is bad, but being healthy is good.

Completely disagree. Would rather be limbless and alive than dead. Constant pain? Constantly take opiates.

Non-ending life (as you describe it) is terrifying.

But non-ending life (in other more positive conceptions) is the literal basis of religions.

There is always the fire option... or nuclear

Reminds me of Elantris by Brandon Sanderson.

Why do you think it isn’t possible? Let’s say they stayed puppies for 5 years. That’s at least as long as humans stay kids.

Life span and childhood won’t be simply controlled, but why in principle couldn’t a puppy stay a puppy for a few years?

Failure of ambition if you ask me, jeez