Don't worry. It's made me look into it more thoroughly and re-adopt the more cautious stance I had when I joined the platform. I won't be using CC images any more. It has totally reinforced my idea that sticking to the sites I chose was the safest option, because most of the lawsuits I've read about have come from Flikr and Wiki where photographers deliberately add restrictions that they know people ignore, then sue them.
BUT saying that, I've decided to go with a 'writer's own photography' policy in my pub going forward, and if that means it fails, or has just half a dozen contributors, that's fine. I didn't want a big problem to deal with anyway. In terms of the sheep pic, it's been on Pixabay since 2014, so I think it's probably fine. I'll be looking at everything and replacing a lot of images on my own stories, and also looking at the pub.
For stories about places in the UK that can be considered 'promoting Britain' Visit Britain Images is a good site. And if contributors are having trouble finding a pic, I might be able to help. I've been lazy using Unsplash because it's easy... but I do have a lot of pics of my own.
I just need a few more grumpy dog/cat pics, to express emotions better than a woodland scene!
I a world where most people have smartphones, to be honest, I find it remarkable that people don't seem to have more of their own pics. I'll be announcing the change and tagging everyone as soon as an article I sent to a publication last night, explaining the situation, gets published.