…”everything hides and stops trying to eat you when it rains.”

Our line were small monkeys in rainforests for a lot longer than we’ve been big hominids living on open plains. Big chunks of our brains don’t even know we ever left the trees, because evolution doesn’t discard instincts that were ever useful – it just buries them under new ones.
Sleep paralysis; plus the sudden feeling like you’re falling when you’re on the edge of sleep; and the sense of comfort when we hear raindrops on leaves...all of that is from the trees. And a lot more. Fear of spiders definitely is. Big spiders specifically lethal to primates are still a part of African rainforest fauna.