You’re still missing the point. Sacrifice was never for forgiveness. Repentance /asking for forgiveness is how sins were forgiven. Messiah was often called the Passover lamb. Do Christians even know what the Passover lamb was for? It wasn’t for forgiveness.
Atonement is a completely different thing.
As for how your sins were forgiven before messiah.
Psalms 86
Be gracious to me, Lord,
For I call upon You all day long.
4 Make the soul of Your servant joyful,
For to You, Lord, I lift up my soul.
5 For You, Lord, are good, and ready to forgive,
And abundant in mercy to all who call upon You.
6 Listen, Lord, to my prayer;
And give
Your attention to the sound of my pleading!
7 On the day of my trouble I will call upon You,
For You will answer me.
8 There is no one like You among the gods, Lord,
Psalms 25
16 Turn to me and be gracious to me,
For I am lonely and afflicted.
17 [
k]The troubles of my heart are enlarged;
Bring me out of my distresses.
18 Look at my misery and my trouble,
And forgive all my sins.
Psalms 65
You who hear prayer,
To You all [
b]mankind comes.
3 [
c]Wrongdoings prevail against me;
As for our offenses, You [
d]forgive them.
Just like they are now.
You have to ask and repent.