Natural selection alone doesn't explain the emergence of things like limbs, eyes, advanced organs, etc.
Yes you could argue 'eventually those things favoured survival so became dominant' however that doesn't explain the emergence of those things in the first place. You could bash around for trillions of years and not see the complexity for eyes arise randomly.
I don't buy into the creationism or religious takes on the issue either, for one the very concept of a deity is flawed as nothing can be defined as 'god', any level of power is simply relative and would have some origin in technological advancement or evolution.
The most likely scenario thus for the origin of life on earth is intelligent design by a species immensely superior to our own, which may have programmatically ingrained the very pathways for life to evolve into the initial dna on our planet. Given the huge distances involved and the energy it would take to travel, there's a good chance they sent this early dna out via some sort of radio or light signal, seeding it to arise on any suitable planets throughout the universe, and even beyond unto other universes. Our earliest ancestor, that primitive bacteria, could have come from a pulse of light sent out long before our universe even existed.