The central idea of neo-Darwinism is that evolution favors the genes that spread best through the population.
A common misconception about Darwinian Evolution is that it maximizes ‘the good of the species’. In reality evolution promotes the propagation of individual genes (sometimes to the detriment of the species).
Evolution does not especially promote the ‘welfare’ of species or individual organisms. It does not promote the ‘welfare’ of genes either: it adapts them not for survival in larger numbers, nor indeed for survival at all, but only for spreading through the population at the expense of rival genes, particularly slight variants of themselves.
Organisms are the slaves, or tools, that genes use to achieve their ‘purpose’ of spreading themselves through the population.
So, while evolution explains biological progress not all evolution constitutes progress, and no (genetic) evolution optimizes progress.