Gods gaining power through belief and worship. I don't really know why I gravitate towards this trope so much, but I almost always use it.

As often as it is done, I do love reincarnation and resurrection. My personal preference is one that forces a previously powerful person to relearn how to live without that power. Or learn the lesson that they rely too much on them. Regaining their power is an option, but I like ones where they don't just have it immediately, or choose not to use them.

For example, in one of my projects, the main character was the most powerful mortal mage probably ever and was the first person to literally rule the world. But, when they reincarnated, they almost immediately nearly killed themselves because they tried to use magic their new body couldn't handle. Instead, they had to live without the abilities that they had relied on so much in their previous life. And he turns out happier for it. He had sacrificed far too much in his past life, and, now, without his powers, he has decided to live without the same regrets.

The whole background premise of my world (although it doesn't come up that much because it happened long in the past) is humans going to Alpha Centauri and then for unstated reasons end up cut off from Earth and kind of have to start anew which I think is quite cliché, but I don't really care because it's just an excuse to do my worldbuilding with humans but without the weight of human history on Earth.

Hubris leads to doom. Usually occultists or zealots trying to control powers beyond their comprehension in my fantasy settings, or scientists and politicians trying to control -natural- powers beyond their comprehension in my SF settings.

Humans being the only race. It's just easier and more fun for me that way.