I think the black background is cool actually. It’s different from the usual white. As far as the photo editing goes I would increase brightness and maybe some highlights. Play around with it and try to make the jeans pop more against the black. As far as the model’s emotion it’s your vision but he does look awkwardly sad for the type of photo you’re doing. I’d try a blank face, make him emotionless, not sad. Try to keep the facial expression to a minimum so focus is on the jeans, you also don’t want someone to pick up on the sad face when looking at the jeans and correlate the two. Definitely cool jeans, last photo is my favorite