There were several covenants between God and mankind. The first was the covenant with Adam. The second was the covenant with Noah. Note that those included all of mankind. What we commonly refer to as the Old Covenant was given to the Jews at Sinai through Moses. That law was then expanded over time, forming what is called the Secondary Law. Parts of the old covenant, including sabbath keeping and the dietary laws, never applied to gentiles. If you read God's instructions to Adam:
Gen 1:29 And God said, “See, I have given you every herb that yields seed which is on the face of all the earth, and every tree whose fruit yields seed; to you it shall be for food.
Notice that meat was not allowed to be eaten. But at the time of Noah:
Gen 9:3 “Every moving thing that lives shall be food for you. I have given you all things, even as the green herbs.
Gen 9:4 “But you shall not eat flesh with its life, that is, its blood.
Noah was allowed to eat "Every moving thing that lives...". That passed down to all of his descendants. It was only with the giving of the dietary laws to the Jews that Jews were only allowed to eat certain animals.
The prohibition against eating blood continued on even to Christians:
Act 15:20 “but that we write to them to abstain from things polluted by idols, from sexual immorality, from things strangled, and from blood.