"In its default configuration, a basic Cloudflare plan has (almost) no settings. It's not like you make a choice e.g. to host only images there. " Correct but

"In its default configuration, a basic Cloudflare plan has (almost) no settings. It's not like you make a choice e.g. to host only images there. " Correct but you could use a completely separate domain for all the images and only enable cloudflare for that domains. (Not a cloudflare customer I'm just pointing this strategy out.)