Those picks don't seem like the kind that Danny likes (with the possible exception of Mannion). Ainge doesn't think that beanpoles are NBA bodies (so no Pokusevski), and he doesn't seek out older players with low ceilings just because they might be ready to play right away (so no Bey). There will be few if any minutes available to rookies in 2021, because Grant Williams and Romeo Langford will soak up anything left over after Tatum-Smart-Brown-Walker-Hayward and the three-headed center get their minutes.
I would expect Ainge to seek out explosive athletes with NBA bodies but minimal experience and the potential to develop new skills in the G League.
In fairness he does have a tendency to choose high floor upperclassmen late in the first round. Especially in first rounds where he has multiple picks. While we forget because Grant Williams is so young, he was a three year player. He's also a high floor/lower ceiling type.
Off the top of my head, guys that fit that profile in Ainge's draft history, in 2004 there were Delonte West and Tony Allen. They mostly punted the first round for the remainder of the decade. They gambled on Gerald Green in 2005 with their only first round pick, but traded #1s to shed salary in '06 and to acquire Ray Allen in '07. In '08 they repeated the Gerald Green error with JR Giddens.
In the 10s they drafted Jared Sullinger in the late first. Sullinger was an underclassman, but he was also one of those high floor/lower ceiling types. One that, alas, ate his way out of the NBA. In that same draft they gambled on the upside of Fab Melo, which busted, obviously (and hurts as there were a couple of upside guys that check Danny's normal boxes in Kris Middleton and Will Barton, I put this one on Doc as he loved big centers).
In the Marcis Smart draft he broke ranks in order to draft James Young, but Young so checked all of Ainge's boxes that he probably couldn't resist drafting him over a high floor pick. The next draft they'd given a draft promise to Larry Nance Jr, only to have the Lakers peach him with the pick in front of theirs, so they gambled on RJ Hunter's shooting keeping him in the NBA.
We'll pass over '16 as the special circumstances draft, but last year the pattern repeated again, a high upside player at #14 and then Grant Williams at #22.
This year is a special circumstances draft given the paucity of high upside guys. But I would be unshocked if they gambled on someone like RJ Hampton at #14. Other likely #10-#20 draftees that fit that high upside/athletic profile from this pool: Patrick Williams, Precious Achiuwa, Devin Vassell, Aaron Nesmith, and Kira Lewis Jr (he's rail thin, but he's also one of the youngest guys in this draft despite being a sophomore, and if he can add 25-30lbs he could turn out to be one of the best players in the pool).
There's a second group of guys that will go #20-#40 that also fit that profile, and I would be unshocked to see one of these names called at 26 or 30: Jaden McDaniels (same problem as Kira), Theo Maledon (the right handed Killian Hayes, but about 30-40lbs lighter), Josh Green, Cassius Stanley (the lack of length is going to impact his defense, but he'll be instant offense in a bench role), Paul Reed (size/mass is a concern in a big). Jay Scrubb also fits that profile, and I'm warming up to him, though he's a complete lottery ticket (I've now watched more JuCo footage than any sane man should, when I have a few minutes I'll do a write up). But I wouldn't be shocked if Boston tabbed him at #30 or #47.
Guys in that same range that fit the high floor group: Robert Woodard II (reminds me a little of Tobias Harris, only he actually plays some defense, not as good offensively, though), Tyler Bey (size, length, athleticism, plays defense, not much of an offensive contributor, though), Isaiah Stewart (they normally like upperclassmen in this category, but Stewart is a rock solid defensive player and modern C with his 6'9"/250 frame and +7 wingspan), Grant Riller (wingspan might be an issue, he's not K-Rex, takes too many plays off defensively, but effective offensive player that could step right into the Brad Wannamaker role), Tyrese Maxey (there's upside here, but he also has a pretty high floor, possibly a more athletic Wannamaker), Xavier Tillman (6'8", but the wingspan means that he can give you C minutes), and Desmond Bane (athleticism's an issue, but he shoots lights out).