So the only way I’ve figured out how to do this is a little tricky. You have to get to ‘Display Settings,’ which I’ve only found one path to.
You have to access your image via clicking on it when it’s in a post (You can make a draft post and stick the image in there). Click on the picture, then click on the little pencil icon that appears above it.
You should see something that says ‘Display Settings.’ There’s a dropdown menu there for ‘Link To.’ Select ‘Custom URL,’ then type in your homepage in the box (don’t forget the ‘https://’!)