I understand about the concern however,
in reading Lenormand, the Snake is meant to look like a snake for a reason. It's a snake. I don't mean it has to be shooting venom, but a cartoon snake wouldn't give me the same feeling as a snake meant to look like one.
As Tag said, the world can be a scary place. Even the cards some deem more negative, can turn more positive with certain cards next to them.
I can understand someone wishing a deck that seems more fairytale-like or playful, but for me, I want the Mice to not look "nice," because I read them as loss or feeling something has been taken, the Bear to look a bit fierce, and the Coffin to look like, well, a Coffin. The cards are about visual cues for the Reader, and we all like different styles, but sometimes there are going to be cards that show up that are meant to not be sweetness and light.
Balance is important no matter what style appeals to you.
I hope you find the PERFECT deck for you. There are a lot of styles and, personally, I think the Vintage German is a good one because it's based on a classic, and is a good one for beginners. The Lenormand Oracle by DiRoberto is also based on the same deck and is inexpensive on Book Depository. You can search here or on Amazon, Book Depository, lots of places under just Lenormand. I know you will find one that appeals to you.
Good luck on your journey.
There are TONS of scans online for Lenormands. Enjoy looking! It's part of the fun to find your deck(s)!