Hello and welcome to itch! Yes, people are generally nice, and also there are rules that do sometimes get enforced, which is great if you are sick of the "total free-for-all" that happens at other sites.
It's tough to just be the "ideas" guy though. If you want to be a designer, maybe you could make a design document where you really flesh out your idea. Something that you could just hand to someone and they could theoretically make a game from it with no further instruction. For this it really helps to have some art to go with your descriptions, so I would recommend trying some asset production yourself or at least cutting together mock-ups using free resources.
Ideas are a dime a dozen, if you want collaborators you'll need something to impress people with!