Why am I still scared of the dark ?

I turned 21 recently and I am still scared of the dark and I don’t know why.

I know a lot of people will say that it’s a normal thing, that it’s natural for a lot of adults to be scared of what they can’t see.

But for me it’s more than just being afraid of a stranger in my house or a real person, I am actually scared of things that clearly do not exist : it,skin walkers, slender man (this one I am really ashamed to admit 😭 please don’t make fun of me). Plus, every time I watch a horror movie I will be scared of the creature in it and the nature of it can be completely different : the doll from Annabelle, the monsters from the descent, and even Jack from Shining scare me to an extent and will keep awake.

I feel really ashamed to feel that way at 21 and I try to get rid of it, but evertime, my mind will play tricks on me even though it knows that it’s irrational.

If you guys have any idea of why I feel that way and how I can try to not be afraid anymore it would really help (I don’t wanna still be afraid of slenderman by the time I turn 50). Thank you in advance.