I hope ypu are not implying that you have no Ideas, because that would be not a very good Premise.
But of Course, different People find different Things scary.
And there certainly is a Time and Place for Jumpscares, but they should always give the Impression that there is something dangerous, otherwise it is just abusing Reflexes. No, if a Sound an Animation comes so sudden that it “makes me jump” (i.e. I feel a slight Sting in my Chest), then that is just a Reflex of my Body, while I myself might just laugh what I see. It must be Fear-inducing, or otherwise it is not even a proper Jumpscare.
However, I am hard to impress when it comes to Horror, and I am in the Classic-SilentHill-Camp, so I personally think that there must be a certain Mindfuck-Value to whatever is being seen. It must make you think and wonder, must awake your morbid Curiosity, but also give you a creepy Feeling that whatever it is, you don’t wanna go near it, while at the same Time some very deep Voice within you tells you that whatever it is you see and how horrid it may look, something about it might be pathetic, beautiful, or even strangely erotic.
A cartoony Witch-Head is none of the above.
Also, in that Demo yesterday I had the Impression that in the Beginning of the Game the Soundscape was relatively eery, at least trying to be, but the longer I player I had the Impression I just heard Thunders, and they were Way the clear for the game taking Place indoors.
Besides, Thunder is not scary. There might be People who, for good Reason, might be scared of Thunderstorms, because a Lightning may strike and hit their House… but you know that there is no such Danger in this Kind of Videogame, so hearing Thunder Sounds might be a nice Sound for the Background, some Ambience, but in a Game it is just by far not as fear-inducing as it could be in Reallife.
However, if I would be playing a Game and find a Memo about a Person who has been hit and severely injured by a Lightning Strike, and THEN I would go out into a Thunderstorm with Lightnings, I might wonder if that Memo was foreshadowing that this could happen to me in the Game, and THEN it would become scary.
I have just played again. Well, no Jumpscare at the Beginning… I went into the next Room, both Keys were lying next to one another. I went back, finished the Game, no Jumpscare-Witchhead at all. Not sure whether this is how you imagined the Game to be played. ;p But it makes me realize that when I spoke of the last Jumpscare before and said that it was well-done, it might just have been Coincidence… so I will describe it…
The first Time I played it, the annoying Witchhead seemed very ridiculous to me… then I had the two Keys and looked for the Exit – it was hard to find, because I had gone far aways from it already. Then I saw the Door in the Distance and headed towards it… but I became aware that only in the most outer Margin of my the Lightcone, there was a bright, pale Stain on the Screen. I stopped because at first I thought it was some Illusion, but when I looked, I saw that it actually was the Head, just floating there in the Air, still and quitely staring at me…
… and WAAAH! it rushes towards me!
That Moment of Silence, of becoming aware that there is something, questioning it, recognizing it, becoming curious about its unusual and calm Behavior… alls of that was a beautiful Setup for the Jumpscare to actually get some Substance.