I disagree about the drafted players not having sufficiently high ceilings especially for where they were drafted.
Sexton's ceiling is an electric and efficient scorer who, if he was in a bench role, would probably be a 6MOTY candidate. In hindsight he's probably the best pick we could have made, though the SGA situation is debatable. I think his defense will improve and not only not be a liability but eventually an asset.
I think Okoro has a pretty high ceiling as an Igoudala-light-type player who can do a bit of everything. May not ever be the best iso player or shooter, but very high bball IQ, makes effective passes, finishes well around the rim, excellent slashing. If he's your #1 guy you probably won't be a contender but he should be a fantastic #2/3, and can switch on 1-4. In a few years, I don't expect him to be the clear-cut best pick at #5 in the draft because I think guys like Vassell, Haliburton, Okongwu, Hayes, maybe even Deni will all be respectable players but generally fill different roles. Probably no superstar talent in this pool but good players, fringe AS players. Who knows, there is always a surprise.
KPJ obviously has a great ceiling and is a good complement to Sexton and Okoro since he can shoot, iso, and pass and has enough length and quickness to switch 1-3. Obviously has other issues that may limit him but he's definitely lottery talent so pretty much by definition this is a high-ceiling pick at #30.
Windler, if and when he starts shooting 40% from deep, will be a fantastic role player. He also seems to be a smart player; lots of times sharpshooters are only good at sharpshooting but Windler is an excellent rebounder and moves the ball well, and should be a sufficient defender.
Not sold on Garland, he's apparently got talent but we haven't seen it. He has good handles but they never result in open looks. His floater is inconsistent at best (I think he missed like 5 of them last night?) and he can't finish through contact or draw fouls like Sexton, nor avoid blocks using creativity like Irving. He's a good shooter who can't make shots and he's undersized (strength + length) and a defensive sieve. His shot release is awful in terms of blockability.
Matt Mooney is likely a future first ballot hall of famer if he reaches his ceiling. I see a blend of Steve Nash and Matthew Dellavedova; the pure PG instincts of Nash but with the girth and defensive grit of Delly, and somehow more whiteness than Nash/Delly combined. At worst he has the perfect build for towel waving and butt slapping, and his face is just annoying enough for guys to want to go at him harder in practice, but not so annoying that you have to look away from the screen; a very careful balance that few achieve.
Dotson is a great pickup as long as there aren't any character red flags. Dude's a straight baller and honestly if KPJ doesn't work out, Dotson is a great consolation (though KPJ likely has much more room to grow and be better a few years down the line; Dotson still has untapped potential too, though).
I would really love this team to emulate the Miami Heat. No pure PG but everyone moves the ball and moves off the ball. Team assists, not individual assists; lots of guys hovering between 3-6 apg. Lots of guys averaging double digit scoring, and a handful of guys who could get hot and go off for 30. Obvious grit and grind. Guys like Sexton, Okoro, Windler, LNJ, KPJ, Exum, Dotson and Cedi all fit this, or could fit this in future (I don't see Garland fitting this as much)... Being in Cleveland, I think this is the only way we can talk about getting close to contention because you don't need a top 5 player in the NBA. Before Jimmy, Miami was at least still very competitive; after Jimmy they are in contention status. Most peg Jimmy as around ~10th best in NBA; I think he's at the top of the second tier of superstars.