Satan does not exist in the earliest parts of the OT before the Babylonian exile. Everything was attributed to Yahweh - good and evil.
If somebody experienced bad things they must have offended god even if they didn't now what it was. The book of Job was a challenge to this worldview. The opening and closing chapters are later additions.
In Babylon the Jews encountered the Zoroastrian religion of Persia with it's battle between good and evil. Good god has a nemesis. They brought this back and incorporated it into their Jewish religion. Now, when Samuel and Kings are rewriten as Chronicles Satan makes his entrance. No longer does Yahweh make David take a census and then kill thousands of Israelites; now in the new version Satan made David do it.
In the 21st century believing in Satan and demons is the ultimate in superstition.
As far as your question about evolution is concerned please do a search for earlier threads. Here is a great place to start...
Please take some time to read this thread carefully.
There is no substitute though for doing your own research. Take your time, it has taken me over a decade to scratch the surface.
Here are some books you will find interesting. Feel free to ask questions, we were once where you are now - some still are.
"The making of the fittest" by Sean B Carroll
"Evolution, what the fossils say" by Donald Prothero
"Why Evolution is true" by Jerry Coyne
"Your Inner Fish" by Neil Shubin
"The Greatest Show on Earth" by Richard Dawkins (Summary of part of it here...)
"The Blind Watchmaker" by Richard Dawkins
"Life Ascending" by Nick Lane
"Endless Forms Most Beautiful" by Sean B. Carroll.