Wherever in a level i save, when i load i always start at the beginning. Is this a technical issue, or was the system made by a moron?

i know what a checkpoint system is, my question is what the bloody "save" button is for if it only saves what level you're on and not your current position or last checkpoint. I's useless

This is what manual says about the save system:

apply the 1.4.2.1 XIII all in one installer patch and then press f5 to quicksave at every checkpoint.

A very stupid save system. Well, at least I only lost 4 hours of gameplay. Of this supposedly 9 hour game.

The save system is indeed broken.
It sometimes not even save between missions, not only checkpoints.
I finished mission 4 or 5, where you are on the roof and use your hook for the first time.
Then new mission started on some snowy location (island or somewhere), I made save and F5 like always to be safe and took a break.
Guess what...
Yes, when I loaded, I am again at the beginning of previous mission.

Whats more, no matter what resolution I set, even if it says 1600x1200 in settings, it keeps displaying 1024x768 in practice.

I like the game and I play a lot of retro since 90s, but I am done with this title, since I do not want to waste my time on repeating same levels I already finished over and over due to some broken save system (I never seen such BS in other, even much older games).