Brook isn't immortal, if his bones gets pulverized he will die again, he said so himself. He's a revived human. I think we already discussed this in length in the past, so feel free to go back and read those posts, and if you guys don't actually have something to add, it's just redundant. It certainly isn't the place to discuss only Brook, this thread is first and foremost about Kaido.It seems to me that the last posts were mostly centered on Brook, while I understand the relation it shouldn't be only one aspect about it, in this case immortality that is discussed, without actually linking it to Kaido. Just because this isn't the chapter discussion doesn't mean the offtopic rule doesn't apply to it. Always try to keep things on topic as much as possible.
And I would say it's too early to tell if Kaido is immortal, and benefited from the ageless surgery, or is just hard to kill. There are many ways to explain why he can't die, for example luck. He could be so lucky he somehow makes it unscathed each time they tried to execute him. We also don't know for sure if he was always suicidal, or just after WB died. We don't know his age either, because if he's older than the average human's expectancy then maybe that proves he's immortal. So we clearly lack a lot of information about him, and it could be we're jumping to conclusions too soon, by assuming he's immortal.He's certainly not invincible, because he lost quite a few times to the other Yonko for example, and imo that is all that matters. Since it would mean it's actually possible for Luffy to beat him.
It certainly looks like Oda is hyping him up by making it appear he's immortal, or that he's simply too strong/resistant to kill.