a little question to the creators, if sans hadn't had the idea of ​​taking frisk out of the underground would it change a lot in axetale's history?

Very much so. It’s very possible that Flowey would have tried to hunt Frisk down, to get the last soul he needed to ascend to true godhood, so Sans would have gone into deep hiding with her, and likely with his brother, too. He wouldn’t have gotten his skull smashed in, Frisk likely wouldn’t have died (I say likely because it’d be a hard thing to keep her safe, as the Underground devolved into sickness and violence), and Aliza would have been born into an Underground far, far different than the one that was intended for her. They would all have still been trapped, unfortunately… and things only get worse from there.