why during cutscene its always like this ... (small spoiler)

[RiceisNice]

Not all of them. In heavensward in particular you are depicted doing a lot of the feats there alone, without any party members in sight.

Only you face the knights of the round.
Only you get eaten by Bismarck.
And iirc, only you are around to see lahabrea's death.

It's a matter of inconsistent depiction. In the same vein of Bismack, you had an entire party with your on your little floating island. Praetorium and other instances (steps of faith off the top of my head) directly refers to you getting an elite group of adventurers, greg acknowledges "fighting all eight of you...". Even in the likes of Ifrit normal when you got captured, the NPCs practically handweave that you can still escape from capture and (paraphrasing) "come back with a group of companions", all of which at the bare minimum would have at least possessed the echo to be able to resist being tempered.

It's not out of the question that there are multiple people who are blessed with the echo, let alone being a chosen of Hyadelyn (since Y'sayle is one herself). The other explaination is that there is a singular warrior of light, and the player character is reliving their experiences through the echo.

As Krile has explained to us, there are lots of different warriors of light. Heck, anyone with the posession of the echo is considered a warrior of light, but this is not the same as the Warrior of Light we play. You can tell even when you first encounter the derplander and he says "So you are the warrior of light, savior etc" I doubt he's running around saying that to every single Warrior of light he runs into. While there are many different incarnations of the warriors of light, like Krile, they all have their own role. But in accordance to the canon of our individual story, we are the only warrior of light capable of the feats we see in the game.

There is also a matter of you being a warrior of light, and you being the warrior of light that's throwing the equilibrium out of balance, whether or not the last statement remains to be true or not-the-whole-truth because this is coming out of an Ascian's mouth.