Kid may be higher depending on his performance against Big Mom. If Law isn't really fighting anymore, it means Kid will be stronger than him.
Marco is not underestimated, reread Marine Ford and Onigashima is a monster who could have replaced Whitebeard.
Luffy just behind Kaido and Big Mom it is justified in my opinion, Luffy does not stop taking the stages since his victory against Katakuri, and his fight on the roof against Kaido. It's no coincidence that Kaido compares him to Whitebeard, Roger, Oden, Rocks and Shanks. He seems to stand up against Kaido in a face to face Kaido seems to enjoy his fight against Luffy. I think he goes as Katakuri comes to see him as his equal.
The tanked this even bigger as imagined attack with even less trouble then expected. Just clapped up the dust and charges to big mum again. That’s casually tanking, the word damage must be unknown for kid.