He attended the all-boys DeWitt Clinton High School in the Bronx, where he met Countee Cullen, who became his lifelong friend.

[6][4] For over three decades Jackman worked as a model, most notably for Ophelia DeVore's The Grace Del Marco Agency.

[3] Jackman was a part of Harlem's gay community and frequented the Hamilton Lodge Ball, an annual masquerade which attracted thousands of costumed men and women dressed in drag.

He frequently escorted single women and was usually king of the Urban League's Beaux Arts Ball.

[5] Jackman spent periods in Europe, particularly in Paris where he met expatriate writer Edouard Roditi.

He was known for being social and mingled with various prominent figures of the Harlem Renaissance such as Langston Hughes, Carl Van Vetchen, Wallace Thurman, Claude McKay, and Countee Cullen.

Two months after the wedding, Jackman and Cullen traveled together to Europe without the bride, which has led scholars to surmise that they were lovers.

Listed as beneficiaries were his sister Ivie Jackman and his friend Mrs. Diana Jean Shaw.

[13] The Cullen-Jackman Memorial Collection at Atlanta University "documents the artistic and creative nature of those of African descent.