This story is so complexed and nuanced that it’s not only about destiny which applies to all characters in this story much like it applies to everyone in real life according to Christianity which is the basis of this story. While Ines and Carcel -just like every character in this story- has their destiny, they still live their lives by their own choices. There is indeed an overarching theme that is similar to Christian theology of foreknowledge and predestination (even just saw the latter in Anne Shirley anime), the author writes the story in such a way that the characters still have their agency or free will. The author also has a knack of subverting cliches and I like that.
I do agree that ONE of the purposes of the 1st TL memories is to help Ines grow and develop but there is so much more to the original life. It is the origin of Ines’s tragedies. Frankly, I find it abundantly much more compelling than starting her original life at Oscar. I would encourage readers to wait to see how it all unfolds because Oscar’s motive started from there and Oscar wasn’t even obsessed with Ines in the first TRUE life like readers seem to think. The story has more revelations ahead before the end.
SPOILER
she wasn't supposed to choose the prince at all from what i read from the spoilers. The prince also have his memories that's why he deliberately planned to make ines his on the 2nd timeline. tbh if the prince wasn't such an a--hole these wouldn't happen. Even on the 1st timeline the prince had a part that led carcel to his death.
you can say that there's a destiny play but I would say it's more like the "god" was giving them chances to make things right by "cursing them" (?) aka their memories intact and redoing their life again and again

I have maybe a random take but I think I would have liked it better if her life with the prince was her first one all along, and she just chose differently with Escalante, instead of him being "the first and right one all along", but maybe that's also because I never liked the trope of lovers that had secretly already met when younger/as children and made a promise or something along those lines to signal fate. It always felt a lot more artificial to me than watching people stumbling through their choices, a lot less about characters' agencies, like everyone is some sort of passive recipient of their destiny. Though I do think it's going to be a lot more nuanced than that as well and this story plays a lot with "destiny" as a concept as well.
I feel like the meaning of these past memories are that they were both much younger and immature in their first lives as lovers, as well as people who symbolized so much power, and hurt each other, but now they are able to communicate properly and learn from their previous mistakes. That would be super interesting also, but we'll see!