Darwin is proof you don't have to be loud to change the world. He was a careful, anxious, almost shy guy who collected evidence obsessively for decades.
On a voyage around the world in his twenties, he noticed how living things varied from place to place. Slowly an idea formed: nature 'selects' — the traits that help you survive get passed on, and over enough time, that builds whole new species.
He sat on it for about twenty years. He knew what it would do. When he finally published in 1859, it landed like a bomb — because the quiet implication is that humans aren't a separate, special creation. We're part of the same tree as everything else alive.
If you're lost, there's something grounding in that. You're not an accident floating above nature. You're related to all of it — the trees, the animals, the people. You belong here. You came from the same place everything did.