Since v. 3 refers to the creation in Gen. 1, life here should refer to the life signified by the tree of life in Gen. 2. This is confirmed by the fact that in Rev. 22 John mentions the tree of life. Since life is in Him, He is life (11:25; 14:6), and He came that man might have life (10:10b). The introduction to this Gospel is composed of this entire chapter; it begins with life (v. 4) and ends with building (vv. 42, 51), that is, with the house of God. Hence, it is an introduction to life and building.
Footnote from John 1:41 Recovery Version of the New Testament