During the prehistory, the prehistory artists emerged to depict through paintings the stories of the time they lived. It is well known that for them the books, rolls, scriptures or even letters did not exist. So, the only to show to the future generations what they experience was through paintings on rocks. Mostly, they talked about the fights they had to get the food or to survive in that era.
The lines 'at last' 'gloomy past' and 'white gleam, bright star' make me say that it is reflecting hopefulness, as opposed to what it was (I assume) like before in the story
