Jamieson, Fausset and Brown on 1 Corinthians 15:47

47. of the earth--inasmuch as being sprung from the earth, he is "earthy" (Ge 2:7; 3:19, "dust thou art"); that is, not merely earthly or born upon the earth, but terrene, or of earth; literally, "of heaped earth" or clay. "Adam" means red earth.

the Lord--omitted in the oldest manuscripts and versions.

from heaven--(Joh 3:13, 31). Humanity in Christ is generic. In Him man is impersonated in his true ideal as God originally designed him. Christ is the representative man, the federal head of redeemed man.