Personally, I do not like "End-of-the-World" scenarios (zombies can not happen at all either) or aliens coming from space to destroy us.
As I do not believe that the Earth itself is billions of years old, I do believe it is older then 6 to 10 thousand.
It isn't really a young planet, it's more in it's late teen-years of life. It's not anywhere close to dying off.
To specific religions, mankind is the supreme ruler of earth and all the creatures found here. To others, we are just warts or annoyances of the planet, and will eventually be eradicated.
Both of those theories are incorrect, in my opinion. I believe that we are not the supreme rulers of earth, because the Earth is it's own living being. Owning that would be slavery.
But I do not believe that we were here by accident. The planet is our mother (we call her Mother Nature anyway) and we are her children in a sense. She cares for us, but we need to start taking care of her. Everyone can do something to help her out, it just takes time.
As for helping the planet, people need to invest more into clean energy. USE THE SUN! We are next to the greatest power source in out solar system and it's just sitting there. USE IT!
Wind power is still being used, but it needs to be sent all over. Not just to big cities.
I don't consider water a good fuel source for technology. People want to use drinking water as fuel for cars and such, but we need to drink that! Leave the ocean water alone too. We can't use that. Stop damming up rivers and use solar power.
As for zombies, it may be fiction, but people are actually preparing for a zombie apocalypse...excuse me? That will not happen!
If our bodies are taken over by a parasite or something, our souls will leave. Our body will be dead. Then if there is no pilot, then the body can't function. Our spiritual energies will not allow something like that to happen. But if it does, there will be a bunch of rotting bodies just lying there. They won't be running around ripping people apart.
Aliens destroying us seems popular now days. But not all aliens are going to be here to take us out. They may be just as excited to meet a new race as we would be. When that happens, the government and/or people better not screw it up for those of us who would want to start a friendship with the aliens.