so theres actually no such thing as the last file modification/creation date according to the os/fs ?
Those are two different things.
You can almost get those things from a stat(2) call:
st_mtime Time when file data last modified. Changed by the mknod(2),
utimes(2) and write(2) system calls.
st_ctime Time when file status was last changed (inode data modifica-
tion). Changed by the chmod(2), chown(2), link(2),
mknod(2), rename(2), unlink(2), utimes(2) and write(2) sys-
mtime is definately last modified time, but ctime isn’t exactly creation time. So no, there really isn’t a creation date. Not one available via POSIX, anyway.