Sorry... but what kind of answer is this?
Kaido was hyped for and he hyped his special lineage, his "Not being a human, but a creature"; an instrument of war. He even said it to Yamato:
Loki too has a special lineage that made other people fear and hate him, only much, much better.
Again, what answer is this?
Kaido was hyped to be the big, baddest thug of his kingdom; Loki was exactly the same, only of Erbaf, the country of War.
Loki surviving as a toddler and not managing to die as a child >> Kaido falling as a 60 YO, dragon man with scales.
On this, Oda made basically a 1:1.
It's not hard: Kaido has elemental powers, Loki has much better ones. Which is expected, since they both are dragons. And once again, Kaido looked like the tiny version of Loki.
As Luffy, as Imu, etc. So Nika is the same as Onimaru?
Doesn't change that there are two dragon fruits and Kaiod turned out to have the cheap version of Loki's.
And once again, Loki got the far more legendary, stronger blut weapon. Reference to Mjolnir and as strong as a top tier itself.
Those are mostyl 1:1 comparisons which Oda likely wanted to make:
Mutant ancient giant > Oni
Falling as a toddler > Kaido at 60
Baddest thug in Erbaf > Baddest thug in vodka
God dragon fruit > Walmart version Dragon fruit
Ragnir > Kanabo
And so on.