It is important to separate what Isaiah just did in the season he just posted as compared to any single season Paul ever had from the comparison of their careers.
The Truth's total career is just phenomenal and Thomas will have to play a long time to come close to that.
But as an individual scoring season, what Thomas just did was truly historic. Not just little guy historic. Not just Celtic historic. But NBA historic. For Celtic history, in terms of total points scored and assists (i.e., total points created) only Havlicek and Bird have posted comparable or better seasons as a Celtic as Isaiah has each of these last two seasons. Last year IT joined them in the 1800/500 club and this year he joined them in the 2000/400 club. Very exclusive membership. Pierce came close, in '04, just barely joining the 1800/400 club.
But in terms of scoring efficiency what Isaiah did this year was incredible. In the entire baseball-reference.com database, among all players who (a) qualified for the mpg leaderboard and (b) had USG and AST percentages above 30%, only _two_ players have ever posted a scoring efficiency (TS%) above 60% while maintaining a turnover ratio (TOV%) below 12%. Here are the 5 greatest seasons of both heavy point-creation usage with low turnovers and high scoring efficiency.
Isaiah Thomas 2016-17 34.0% USG, 32.6% AST, 10.7% TOV, 62.5% TS
Michael Jordan 1988-89 32.1% USG, 34.7% AST, 11.9% TOV, 61.4% TS
LeBron James 2008-09 33.8% USG, 38.0% AST, 11.0% TOV, 59.1% TS
Dwyane Wade 2008-09 36.2% USG, 40.3% AST, 11.6% TOV, 57.4% TS
LeBron James 2005-06 33.6% USG, 32.8% AST, 10.7% TOV, 56.8% TS
These four numbers sort of form the holy foursome of offensive point-creation indicators. They cover, volume, scoring efficiently and assisting your teammates while not turning the ball over.