Natural selection is simply the idea that all living things want to survive and reproduce.

Along with this each new being could have small mutations that make it different from others in it’s species.

Those beings born with a mutation that makes them less likely to be killed before reproducing will pass on their mutation to the next generation, meaning there will be more of that mutation in the next generation.

Continue this process many many many times and you get evolution through natural selection.

It’s not some great plan, it’s millions of individuals scrapping for survival in the face of a dangerous and uncaring world.

While evolution and natural selection conflicts with Intelligent Design, it is perfectly compatible with a supreme creator and spirituality. Neither proves or disproves the other.

The common belief, though, is that life as we know it can occur through chance.

But, I just want to make it clear that it is valid for you to believe a creator is necessary for natural selection without conflicting with it.

Natural Selection describes the process and the outcome, not intent. It is also situational, where different types of plants and animals fill different kinds of roles at different times because of overall pressures and opportunities from the environment.

Pandas eat bamboo, a very low energy source, in their environment because of environmental pressure. Kodiak bears get absolutely massive on their island because of the prevelance of seafood (whales) that wash up and provide an opportunity for more energy dense food sources. Neither are the result of design, just local environments.

Crocodiles survive extinction events because of their biology allowing for long periods without food and water. But they aren’t successful in cold climates for the same reason. They are vulnerable to other pressures like overhunting, but their other traits tend to discourage being eaten. Something still eat them though! Their immune system is crazy strong because it improved due to where they were successful, stagnant waters with a lot of bacteria.

Bats are the opposite, very fragile physically. But the species have adapted to communal living with fast reproduction and a strong immune system due to that proximity with each other to be massively successful on a global scale.

None of these are designed, and birds on islands being very different from those on mainland because they fit into different roles is a very easy way to see that there is nondesign, just adaptation given enough time.

Since the very beginning the life that was successful was the life that successfully reproduced. That just continued since that point in time, so all current life is also the life that successfully reproduces whether consciously or not.

I often compare Natural Selection to Survivorship Bias, because as far as I can tell that is what it is.

There is no “drive” or mythical force to be better. A mutation occurs and the result works or doesn’t.

Those that work have survived until today, and those that don’t failed to reproduce sufficiently to reach today.

That said, today we actually have what I call “Un-natural Selection”, and that is when we humans take something that would have failed naturally and ensure its success through our intervention. Think seedless plants or humans/animals with chronic disabilities. Natural selection would likely have eliminated them for failure to function or reproduce, but through our will they endure. For now.