I don't think Josh Jackson is Ainge's guy. They're definitely targeting Hayward, already have Crowder, and drafted Brown last year. I really could see Ainge liking several of the guys in the top 10, and continuing to trade down if he can pick up assets. The idea that he needs to start turning these assets into superstars, when the Celtics were already the #1 seed and have the ability to a free agent this summer, is wrong IMO. They can potentially add Blake Griffin or Hayward this summer, and/or trade for Carmelo of Love, without giving up a pick this year. You certainly wouldn't want to give up the #1 pick for any of the players potentially available to you. A Paul George rental isn't worth the #1. A future pick, Crowder, and Smart would probably be a good starting place for a Love trade.
It wouldn't surprise me to see Ainge trade down again at #3 with Knicks for pick 8 and a future pick. Or with Kings for picks 5 and 10.
Ainge is patiently waiting for the opportunity to cash his assets in for a really transcendent player. A player like Anthony Davis. But also someone like Greek Freak, or KAT, or Porzingis.