Source: the ESPN College Basketball Encyclopedia, which came out in 2009. It lists a first and second team of “consensus All-Americans, meaning they combined the listings form all recognized sources to create the two teams. For years after 2009 I looked up each season on Wikipedia. Freshmen were eligible during the World War II through Korean War Era and again from 1973 onward.
1944 Arnie Ferrin, Utah 12.5ppg (his team won the national championship)
1946 Tony Lavelli, Yale 21.3ppg
1983 Wayman Tisdale, Oklahoma 24.5ppg 10.3rpg 0.8a
1988 Mark Macon, Temple 20.6p 5.6r 2.9a
1989 Chris Jackson, Louisiana State 30.2p 3.4r 4.1a
2003 Carmelo Anthony, Syracuse 22.2p 10.0r 2.2a (his team won the national championship)
2006 Tyler Hansbrough North Carolina 18.9p 7.8r 1.3a
2007 Kevin Durant, Texas 25.6p 11.1r 1.3a
2007 Greg Oden, Ohio State 15.7p 9.6t 3.3b
2008 Michael Beasley, Kansas State 26.2p 12.4r 1.2a
2008 Kevin Love, UCLA 17.5p 10.6r 1.9a
2010 DeMarcus Cousins, Kentucky 15.1p 9.8r 1.8b
2010 John Wall, Kentucky 16.6p 4.3r 6.5a
2011 Jared Sullinger, Ohio State 17.2p 10.2r 1.2a
2012 Anthony Davis, Kentucky 14.2p 10.4r 4.7b (his team won the national championship)
2012 Michael Kidd-Gilchrist, Kentucky 11.9p 4.9r 7.4a (his team won the national championship)
2013 Marcus Smart, Oklahoma State 15.4p 5.8r 4.2a
2014 Jabari Parker, Duke 19.1p 8.7r 1.2a
2014 Andrew Wiggins, Kansas 17.1p 5.9r 1.5a
2015 Jahlil Okafor, Duke 17.3p 8.5r 1.4b (his team won the national championship)
2015 D'Angelo Russell, Ohio State 19.3p 5.7r 5.0a
2015 Karl-Anthony Towns, Kentucky 10.3p 6.7r 2.3b
2016 Ben Simmons, Louisiana State 19.2p 11.8r 4.8a
2017 Lonzo Ball, UCLA 14.6p 6.0r 7.6a
2017 Malik Monk, Kentucky 19.8p 2.5r 2.3a
2018 Deandre Ayton, Arizona 20.1p 11.6r 1.9b
2018 Marvin Bagley III, Duke 21.0p 11.1r 1.5a
2018 Trae Young, Oklahoma 27.4p 3.9r 8.7a
2019 R. J. Barrett, Duke 22.7p 7.6r 4.3a
2019 Zion Williamson, Duke 22.6p 8.7r 2.1a