Survival of the fittest, evolution and the descriptive/prescriptive laws of nature

When you hear about Darwin and the evolution theory for the first time, you are almost always told it is the survival of the fittest, the law of the jungle.
I always felt uncomfortable understanding evolution in these terms.
Although historically, evolution theory radically contradicted the world view of monotheistic religions, it still somehow managed to imply the hand of god hiding somewhere, controlling everything.
Each generation will produce offspring, the fittest among them will survive, the weakest won't, and so on, and so on,
You might feel equally uncomfortable when you try to understand the laws of nature as prescriptive forces
Do we understand that an electron moves the way it moves because it has to comply with the various physical laws of motion andconservation of energy OR the electron moves the way it moves, and the physical law is merely a description of its movement.
If we understand evolution in this light, then the theory transforms itself from survival of the fittest to the fittest being the one who survives.
We actually don´t know who is the fittest, and the fittest, the way we understand it, is not always the one who survives.
What we can say for sure, is that the one who survives will probably reproduce. The ones who do not survive will not reproduce, not because they are weaker, in our definition of weak, but because they are simply not THERE anymore, whether due to hazard or other reasons