I think that it would be really helpful if you could preview the primary photo and adjust it to your liking, especially for people who don’t like to crop their photos to a 1:1 ratio. You could crop a photo so it displays well, but if you can’t use multiple photos you either have to not show the full photo at all or use a photo that doesn’t display the animal optimally.
When you are editing your ad, up in the right hand corner you will see a Public view button. That allows you to look at how the public will see your ad before save and finishing. You will need to save and continue editing first of course. I hope this is somewhat helpful
I also recommend looking at the size and format of the images you are taking.
Remember that the majority of people are using small screened devices where a huge file is not necessary and will actually make the image underperform.
But, i love the idea of being able to crop on site. No idea how doable that is but definitely a cool thought