Genuinely asking: would/should the ownership rest solely with the person promoting the model, or would part of all of it belong to the model itself (and/or its creator)? My hunch is that this is a somewhat unprecedented scenario, so comparing Midjourney to a tool like Photoshop wouldn't be completely accurate—in the sense that of course Adobe doesn't hold the rights to things you make in Photoshop—but there could very well be established cases I'm unaware of!