We do have a slow birth rate. The population is increasing because we have an even slower death rate. It isnt foretelling an event there is no need to read into it, simply healthcare and food production means the population is not balanced by death.
As for purpose. There is none. I find the best way to think of it, which suits my atheistic, theistic, agnostic mindset (ive one for every day of the week!) Is that the entire universe is made of atoms and particles, there are in a simple form and via fusion in the stars over billions of years they become a little more complex, they become molecules. Then these particles, the substance of the universe settle into planets and every billion billion planets or whatever one has enough of the right particles,atoms and molecules, plus the right heat to begin to come to life. Evolution begins which is best described as a process moving the simple to the complex and via this process the molecules are aranged into increasingly complex patterns. first we have single cells, then multicells, then moss, plants and animals. Finally the universe after a very long wait has created ourselves - a system of molecules so intricately complex that it is able to comprehend itself and observe its nature as a molecular being. Thus atoms learned they existed and so we are the eyes and senses of the universe itself. When we look out at the stars, we should remember our bodies and minds were created by them, we are the stars observing themselves!