Attempting to move back to the original question here instead of the Abraham-Chosen People-Isaac-Sacrifice side discussion...
The Abraham and Isaac story is actually more about the “dying for sins” topic than you might realize.
There are too many parallels to these two events.
When God spoke to Abraham and told him he needed to go and make this sacrifice. He told him to go to another location that was a 3 day journey. He sacrificed daily there at home but this time it had to be at a certain location. It’s the same location, 1400 years later Jesus died in the crucifixion.
God said, "Take your son, your only son, Isaac, whom you love, and go to the region of Moriah. Sacrifice him there as a burnt offering on one of the mountains I will tell you about." Isaac was not Abrahams only son. He had an older son Ishmael, by his wife’s handmaiden Hagar. But those same words are used later to describe Jesus
Isaac was about 33, as was Jesus. Both carried their own wood up to the sacrifice location. In Abraham’s case, before he did it, an angel told him not to do it. The angel said that God himself would provide the sacrifice, and then Abraham saw a ram caught in the thickets, and then he gave a ram for the sacrifice instead. 1400 years later God did provide the final sacrifice.
Before this all happened he had promised the world would be blessed through his son Isaac, just as the world was blessed through Jesus.
Abraham had probably more faith in God than any one, it stands to reason he believed that if he had to go through with this then God would resurrect Isaac, he told his wife they would both be returning. He had no reason to believe his son would die when he had not yet married or had children. God promised through Isaac’s seed the world would be blessed.
There are other parallels but these are the high lights. The story of Abraham and Isaac was a shadow of something to come. The crucifixion.