Why do I always get curbstomped in normals so badly?

I can play ranked at my elo (Silver 2... I never claimed to be good.) and win 1/2 to 2/3 of the games I play. Then I can spend the next week playing normals and lose 3/4 of my games. I seem to always get matched against far more skilled and more coordinated opponents in normals than in ranked, and I am really struggling to understand why. It's getting really frustrating despite my best efforts to enjoy it. I just want to play a casual game against other casual players, get my first win and move on. Instead I end up playing what feels like a ranked 5s team 2-3 whole divisions above me. And it's a consistent theme I've noticed in the past few months, not just a one-off thing. Almost every time I play normals it feels like I'm not even on the same level as my opponents. Ranked actually feels easier at this point than normals.

If ranked is for being super-serious, and normals is for getting curbstomped by people vastly superior to myself and my team, what am I supposed to do for playing casually and trying new champs? Why do normals feel so much harder to play?