Of that list I'm going to immediately cut out the guys who have proven themselves to be 'the guy'. So that's LeBron, Kawhi, Curry & Durant.
In the next bracket are guys who it only seems a matter of time before they do, based on their talent level. For me, those guys are Giannis, Luka, AD and Harden. I'm not saying they're all sure things, but rather they comfortably have the talent to be 'the guy'.
Then there's the next tier. Guys with either obvious flaws, but All-NBA talent is definitely there. That includes KAT (defence), Jokic (defence), Lillard (defence / help), and Embiid (conditioning & health). I think that some of these guys definitely could win a ring, they just need certain pieces around them. Jokic needs a better partner than Murray, KAT needs a better situation in general, etc etc.
My next tier after that is young guys on the right path. Out of those listed, that's just Tatum. I don't think Simmons is on the right path, as he hasn't really made strides so far, and I view Tatum as having Kobe-esque potential, whereas Simmons is more of a bigger, worse halfcourt Rondo.
Finally, after that, are guys either too old, or too old to develop the ability to be 'the guy'. This is CP3, Butler & PG13.
So, I would list it, in order of most likely to be 'the guy' on a ring winning team to least likely as it stands now:
Above the line are those I think capable of being the guy as it stands right now