Explainer / Messiah

Colossians 1:15

who is the image of the invisible God, the firstborn of all creation;

ὅς ἐστιν εἰκὼν τοῦ θεοῦ τοῦ ἀοράτου, πρωτότοκος πάσης κτίσεως.

Greek

What we did

We kept the ASV's wording.

Why

εἰκών, "image."
The same idea of "image" is used of humanity made "in the image" of God (Gen 1:26–27), and Paul uses εἰκών of the man as "the image and glory of God" (1 Cor 11:7).
ἀόρατος, "invisible, unseen."
The same word describes God in 1 Tim 1:17; compare John 1:18, "no one has seen God at any time."
πρωτότοκος, "firstborn."
In the Tanakh the word carries rank as well as birth order.
More
"I will make him firstborn, higher than the kings of the earth" (Ps 89:27) is said of David, who was the youngest son. Israel is Yehovah's "firstborn" (Exod 4:22). Ephraim is called "firstborn" though Manasseh was older (Jer 31:9). "Firstborn" keeps both senses open, as the Greek does.
The same title three verses later
Colossians 1:18 uses the word again in "the firstborn from the dead."
πάσης κτίσεως
is a genitive, "of all creation," and the ASV renders it that way.
More
We kept it rather than supplying a preposition such as "over."