No, no at all. The thing is that mortality is a popular way to make a character weaker but in case of Absolute Immortality, you can make it even more interesting with this if your character is live and creative. For instance, you could compose a story about journey this character throughout times and express how they change. With AI, it's likely this person gains a lot of knowledge, extreme skills and hyper experience. You can make a character that would be ex extension of human if it was eternal and indestructible since it has a whole eternity ahead. I hope that helps you.

Nah bc peeps like lobo, deadpool, doomsday, wolverine etc. are some of my favorite characters, & instead of them plowing through planets or holding up 3x earth's size they are just really resistant. (ik lobo & doomsday however do have some ridiculous strength feats)

Not really. It depends on the character and how the writer portrays them. The character needs to be more centered around their personality rather than whether or not the character is in danger.

It all depends on how the character is thought up and used in the story. Some of fictions most popular characters are immortal.

Sun Wukong can’t die, and he’s far from boring.

I think they would be cool if they kill everything and everyone in all realities

Yes absolutely.....if you do it wrong. I mean someone who can’t die and just gets into problems and they can’t die. So it slowly drains their sanity away until they just......idk do horrible things. That’s certainly not boring. Someone who has no flaws and can’t die. That’s it. Then yeah. That’s is certainly boring.