Hi Dreamsa
Fossils can be destroyed by anything - nature, humans, animals.
Humans and animals don't go out and destroy them on purpose, it's just that sometimes we don't see them and walk or build over the top of them. The weather is constant, it is and always will be on this planet. A drop of water falling on a rock once a day for a few million years will change the shape of that rock just a little, but that's basically how the weather is changing everything around us. A rock is a hard substance. That same drop of water falling once a day on say a plant, will probably change the course of the way the plant grows ever so slightly, just because of that drop of water.
Maybe you will become a geologist or an archeologist one day, and you'll learn all about time, and weather, and their relationship to our planet.
The wonders of nature are there for everyone to enjoy.
Cheers
Teri