It was too late for Man — Senility

The key word is creation, which can mean that which God has created _{(OED 4a)}, or a painting by man.

It was too late for Man－¹
But early, yet, for God－
Creation－impotent to help－
But Prayer－remained－Our Side－

How excellent the Heaven－⁵
When Earth－cannot be had－
How hospitable－then－the face
Of our Old Neighbor－God－

(F.689/J.623)

[1] late for Man: the late years of man, the senility.
[2] early, for God: a painting of Jesus that can exist much longer.
[3] Creation: a production of human intelligence, a painting or statue.
      Creation impotent to help: the painting of Jesus cannot help the senility.
[4] Prayer remained: people can only pray.
[5] excellent the Heaven: the paradise after death.
[6] Earth cannot be had: the mortal world cannot be obtained; about to die.
[7] hospitable, the face: the welcome face in the painting.
[8] our Old Neighbor God: Jesus' painting in a nearby church.