Baldersash! LOL
Satan is no more real than god. The very word itself is an admitted manmade invention. TO be more specific, a Hebrew one. IN the Torah, and early Hebrew religious writings, "hasatan" was the word given to mean "enemy." Or "foe." They used it in many different cases, it was sort of a blanket, catch-all term, often used in describing a human, such as form a rival tribe or ethnicity.
Then the word, like so many things in religion, was skewed and blown way out of proportion, and given supernatural qualities. Such as "ha-SATAN: being god's chief rival and fallen former right-hand-man in Heaven. The word can also mean "the deciever" as in a crafty, manipulative foe.
Another misconception in all this fictional and mythical Devil business is the name "Lucifer." Which came from a mis-translation when the Septaguint came out, which translated the Hebrew Bible. The name means "Light Giver" but was originally referring to the King of Babylon. NOT ha-SATAN.
All religions have a supernatural Evil Foe. Even the Buddhists have their "Mara" who tempted the Buddha when he sat under the Bodhi tree for 40 days seeking enlightenment.
(Gee, another "40 Day enlightenment thing, like the Jews wandering and then Jesus in the wilderness, tempted by Satan! LOL. Message to the Jews, since the Buddha came 500 years BEFORE: "Borrow much mythos ideaas? LOL)
But yeah, inventing gods and evil entities--This is mere human nature. As is the obsession with seeking patterns and causes for things even when there are none. An undesirably by-product of our evolved minds. Just like ALL religion is. And talk of invisible gods, adult versions of invisible childhood freinds. Just like Satan is an adult version of the old childhood boogie man, or the monster under the bed. LOL.