No matter which side of the fence you sit on, there's no empirical evidence for God or any other deities or supernatural beings. If there were evidence, this discussion wouldn't need to exist.
Scientists tend not to believe in anything supernatural because, well, their job is all about things that can be proven and tested and observed. It's just logical. To them, everything in the universe can be explained by nature and physics and mathematics, so there's no need for a creator or anything like that.
Non-scientists don't think that way, and so they adopt religions and spiritualism and beliefs in the supernatural in order to explain the stuff that makes no sense to them otherwise. There is also the powerful promise of a karmic afterlife. But as for proof, they have none. Their beliefs are, well, beliefs, guided only by faith and hope and emotion. There is no proof of any god, but some people don't really care, I guess.
As for whether science is man-made, that's a weird question. Science is all about experimentation and observation in order to attain new knowledge, so technically that means dolphins, orcas, rats, and crows are capable of performing science, too. Which means the answer is "no." When an animal reaches a certain intelligence threshold, science will naturally come about in some form or another. Maybe figuring out that ice sheets rock back and forth and using that information to feast on some penguins isn't the highest form of science, but it IS a science.