RPG Maker is still a thing? Yes, you can use assets for your own personal things but you can't legally distribute it / call it your own. Everyone uses copyrighted assets for RPG Maker, ever since RPG Maker 95 but they are just fan games and not intended for distribution but educational purposes. SE lawyers might disagree but I've never seen any fangame end up in legal trouble with SE. Nintendo on the other hand.... lol