The command forbidding humans ingesting blood was commanded long before God commanded it to Israel.
Possible indirect forbidding of consuming blood, by possibly consuming meat also being forbidden.
Why there is no direct mention of God forbidding humans to not consume blood before the flood, God might had forbid pre-flood humans to not eat meat (the flesh of animals and especially not humans since that would be murder): One reason for this is when God first created humans on the 6th day of creation he says they were to eat plants or/and their fruit/seeds they produced for food:
Genesis 1:29
“Then God said, ‘I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food.’”
Notice God says nothing about the animals he previously created a being also given to humans for food! (The absence of God telling them animals were also food strongly hints that God did not allow humans to eat meat or possibly any other edible products coming from an animal: like eggs or milk) why the Bible records that loyal humans to God were allowed and did kill animals (and even God himself might have killed an animal to get its skin for Adam and Eve to wear) it’s only recorded that they killed animals for either their skins to be used for clothes or to be burn up as a sacrificial burnt offering to God; nothing is ever directly mentioned as animals being killed for food.
If it’s true meat was not to be eaten, as it’s hinted in what is recorded happening before the flood, then the blood within the meat was definitely not be eaten!
However, the vegetarian diet (at least loyal) humans might have had before the flood, soon changed once the flood was over; because as a part of the new Noahic covenant God made with Noah and his descendants, he now specifically stated animals were now to be food just like the former plants had been:
Genesis 9:3
“Everything that lives and moves about (that is all animals) will be food for you. “
What God says confirming this strongly proves humans were forbidden to eat meat before the flood: God states he is now giving them both plants and animals for food: now covering everything edible for a human on Earth:
Genesis 9:3
“ Just as I gave you the green plants, I now give you everything.”
BUT along with giving Noah and his descendants meat to eat he now warns them when they eat meat of a dead animal, they were also forbidden to eat the blood (called lifeblood here) inside that animal!
Genesis 9:4
But you must not eat meat that has its lifeblood still in it.”
The blood had to be drained from the dead animal so all (or at least most of) the blood would be out of the meat before they could eat the animal’s meat. This is the first direct command by God forbidding humans to ingest blood; and this was so important to not ingest blood that even the meat had to be (for the most part) blood free:
Therefore, no consumption of blood was allowed, and this was a major part of the Noahic covenant once animal meats seemed to have been now allowed by God. Unfortunately, As the Noahites began to worship other false gods, they began to forget certain parts of the Noahic covenant God commanded them to obey; sadly, one of those was not consuming the blood of animals:
Unfortunately, As the Noahites began to worship other false gods, they began to forget certain parts of the Noahic covenant God commanded them to obey; sadly, one of those was not consuming the blood of animals:
Sadly, many Noahic nations began to eat the blood of animals with their meat and some even purposefully added the blood from other animals to meat and stews just because they liked the taste it gave [1]. And many (if not all) began to eat the blood of animals they ate and began to sin against God’s command to never eat blood: and some Noahic nations did not just stop with animal blood either: some even purposefully drunk human blood! (which is definitely evil and demonic to God!).
But regardless of the majority of humans breaking this command, God, though it is not directly recorded either, most likely commanded Abraham (and his descendants) to forbid them to eat blood if they were ignorant of this rule like most Noahites seemed to be. So most likely, Abraham did not eat animal blood (and Definity not human blood!) but rather drained the majority of the blood out of his meat and it’s also very likely his descendants Isaac and Israel (Jacob) also did not eat blood knowing this command from their father/grandfather Abraham.
Sources:
[1]
[1] Thoughtco “Ancient Egyptian Cuisine and Food Habits” By N.S. Gill on April 20, 2019
Website:
https://www.thoughtco.com/foods-in-ancient-egypt-118392
[2] Ancient Mesopotamia “Ancient Mesopotamia Recipes of Food” by Ankita Bhugra and Thulasi K.Raj on Jan 17 2023
Website:
https://ancientmesopotamians.com/ancient-mesopotamia-recipes-of-food.html