Jumpman is not literally Mario.
He is an villainous version of the plumber who is present in Donkey Kong Jr. and the original arcade game.
An extremely appealing side of Mario who abuses animals with his whip to do his evil bidding in the sequel, contrasted to the light-hearted Mario we know today.
Jumpman's different personality and the weapons he would offer from the classic Donkey Kong arcade games, ranging from hammers to summoning chained animals to his whip would make him a stand-out character that would not make him literally Mario. As interesting as Donkey Kong Jr. and Stanley could be, I personally think Jumpman would have the edge when choosing a Classic DK character because of his evil characterization.
I think he holds a decent shot of getting in as the "surprise" character whom would fall in the likes of Duck Hunt, ROB, and G&W (carrying history for Nintendo with the arcade game helping the company dominate in the video game market), but I personally expect Hanafuda to happen.