I wanted to make a flat world just surviving alongside the guard villagers against the raids, but when I set to survival they started attacking me. I had to kill some villagers while in creative. I have also turned the gamerule forgivedeadplayers to true. Does not work. Please help.

si me pasa lo mismo a mi también me matan y vuelvo para recoger mis cosas y vuelven a matarme

This is because you have a low village reputation, to fix this either move to a new village or find a way to up your reputation with the villagers by trading with them.