As of now kaidou is the strongest. Even if the title of " strongest living creature" refers to kaidou's physically strength, he is still the strongest. The guy fell from a sky island and survived with out a scratch and by the looks of it, it seems he didn't use haki for protection I mean how do you dent the guy. As stated in the last panel of this chapter he is the strongest 1 vs 1. It all makes sense when we look at how things played out when whitebeard went to war with the marines and news that kaidou been intercepted by shanks was revealed. Shanks moves with his crew where as kaidou is always alone (because he wants to kill himself) and at that time shanks had his crew to confront kaidou who was alone meaning kaidou was probably at a disadvantage. All in all kaidou probably didn't fight shanks and his crew, shanks probably told kaidou to jump off sky island and he would die quicker that way or something silly cuz shank tries to avoid fighting.
As far as shanks vs kaidou 1 vs 1, kaidou will win because his body is durable and we know weapons dont hurt him. Shanks might have a chance if he uses haki but kaidou will be pretty much indestructible if he uses his arment haki for protection. Maybe if shanks got a df in future he would win but right now it really is a mismatch in kaidous favor if u look at it carefully.
Black beard might stand a chance because of hax dfs but he hasn't mastered his df to its full potential as of yet and kaidou is most likely a df user (most likely a zoan type) should be op for sure and he has mastery over it, kaidou has been around for a long time where Blackbeard just ascended to the title of yonkou.
White beard was allude to by kaidou in the last panel of this chapter, as kaidou was blaming white beard for kaidous inability to die. It seems white beard in the past defeated kaidou using his df which has quite the destructive power as far as we have seen and white beard in his prime probably had better usage of the df so it is a reasonable assumption to make that white beard defeated kaidou in the past but white beard spared kaidous life, kaidou feels dishonored and went around trying to kill him self.
In general Kaidou is the strongest 1vs 1 as of now. Only time will tell if shanks or BB will be able to defeat kaidou.
P.S I am a shanks / luffy fanboy, just playing devils advocate.