Hmm, best current American born player. Tatum certainly has a case. the Ringer top 100 has him 7th, 5 of the guys ahead of his are all foreign born including SGA who is Canadian.
Kawhi is 6th, Steph is 8th, Durant 9th, AD 10th, Booker 11th and Lebron 12th. I think he's in roughly the same tier as that group of guys, certainly the one with the biggest runway given his age.