Why do you think kirby is so high up?
I don't think it's really that shocking. Kirby was super good in Smash 64 before being nerfed into uselessness in Melee. In PM, everything that was terrible about him has been undone (no more escapable throws, no more horrible dash attack, attacks do actual damage again, etc), and he's actually gotten some nice buffs too, like drastically faster Down B and his new Cutter Dash. Basically he's just really well-rounded and powerful now. He's also got one of the scariest gimp games around because he can go super deep for those kills and not really have to worry about not making it back, and that's pretty important in this game now that recoveries are so much better.
And yes, if you're not convinced yet, just watch Chu destroy some people with him. Sure, Chu is too good in general, but it still gives you a feel for how good some of Kirby's tools are.
I like the just general tier idea in theory (just having like 3 tiers), but when I look at it it just seems like youre claiming there is definitely difference between those tiers while having some more tiers (+ and -) you can show more that characters are close and/or can easily be moved around. But with big tiers it seems like big jumps, but I know its probably not intended that way and your tiers are 'close' to each other.
The difference between the bottom of one tier and the top of the next isn't too much. Apart from Jiggs and the ICs, the game is pretty decently balanced overall. Very few matches feel really lopsided, though some matchup + stage combinations are clearly bad.
I want to kick Ganon down a few spots on your list and tell Captain Falcon that everything will be alright. Telling a Falcon that he's worse than ganon is offensive to knees everywhere.
Honestly it's almost impossible to know how to order that tier. Those characters all have issues which give them some bad matchups but it's all going to come down to the tier placement of the people who beat them. I do think Ganon could potentially be better than Falcon though, for the simple reason that Ganon got buffs from Melee while Falcon didn't.