But tell me when it becomes a RPG, it’s basically a video game system ported to tabletop
Uh.... tabletop came before videogames...
Anyway, no. An RPG is a Role Playing Game, it's a game where you take the role of someone, either created by you or given by the game (be it a videogame or not), and you experience the things that happens to that character.
Saying that TTRPGs are video games ported to TT is like saying that Lord of the Rings is a story written within the DnD lore. It's completely wrong.