[1][2] Landman was born on 19 November 1998, in Harare, Zimbabwe, where his father, Shaun, was playing international rugby.
[3] He attended Monte Vista High School and played baseball, rugby and football.
Over his four varsity years Landman amassed over 1,000 yards receiving and made over 160 tackles, 15 sacks and 4 interceptions.
In his senior year Landman led Monte Vista in a state playoff run.
He was awarded All-NorCal High School Football Team by MaxPreps and East Bay Defensive Player of the Year by the San Jose Times.
He finished with two sacks, 110 total tackles (66 solo), one interception, three passes defended, and three forced fumbles.
[26] Landman has two siblings: a brother, Brenden, who plays college football; and a sister, Ocean Trail, who swims collegiately.