#1 The beginning of Genesis never says man did not eat meat.
#2. Gen 1:24-26 from the very beginning YHWH made cattle which in Strong’s it is had livestock / cattle which is literally a domestic animal. We see in Gen 4 what kind of domestic animal man kept - sheep. What are sheep for? Primarily eating and sacrifice from a comprehensive biblical perspective!
#3 The book of Jasher expresses exactly what these animals were for, read it for yourself.
13 And she called the name of the first born Cain, saying, I have obtained a man from the Lord, and the name of the other she called Abel, for she said, In vanity we came into the earth, and in vanity we shall be taken from it.
14 And the boys grew up and their father gave them a possession in the land; and Cain was a tiller of the ground, and Abel a keeper of sheep.
15 And it was at the expiration of a few years, that they brought an approximating offering to the Lord, and Cain brought from the fruit of the ground, and Abel brought from the firstlings of his flock from the fat thereof, and God turned and inclined to Abel and his offering, and a fire came down from the Lord from heaven and consumed it.
16 And unto Cain and his offering the Lord did not turn, and he did not incline to it, for he had brought from the inferior fruit of the ground before the Lord, and Cain was jealous against his brother Abel on account of this, and he sought a pretext to slay him.
17 And in some time after, Cain and Abel his brother, went one day into the field to do their work; and they were both in the field, Cain tilling and ploughing his ground, and Abel feeding his flock; and the flock passed that part which Cain had ploughed in the ground, and it sorely grieved Cain on this account.
18 And Cain approached his brother Abel in anger, and he said unto him, What is there between me and thee, that thou comest to dwell and bring thy flock to feed in my land?
19 And Abel answered his brother Cain and said unto him, What is there between me and thee, that thou shalt eat the flesh of my flock and clothe thyself with their wool?
20 And now therefore, put off the wool of my sheep with which thou hast clothed thyself, and recompense me for their fruit and flesh which thou hast eaten, and when thou shalt have done this, I will then go from thy land as thou hast said?
21 And Cain said to his brother Abel, Surely if I slay thee this day, who will require thy blood from me?
22 And Abel answered Cain, saying, Surely God who has made us in the earth, he will avenge my cause, and he will require my blood from thee shouldst thou slay me, for the Lord is the judge and arbiter, and it is he who will requite man according to his evil, and the wicked man according to the wickedness that he may do upon earth.
23 And now, if thou shouldst slay me here, surely God knoweth thy secret views, and will judge thee for the evil which thou didst declare to do unto me this day.
24 And when Cain heard the words which Abel his brother had spoken, behold the anger of Cain was kindled against his brother Abel for declaring this thing.
25 And Cain hastened and rose up, and took the iron part of his ploughing instrument, with which he suddenly smote his brother and he slew him, and Cain spilt the blood of his brother Abel upon the earth, and the blood of Abel streamed upon the earth before the flock.
Lastly regarding the vegetarian confusion in reference to Noah that is referencing not eating meat with the blood still in it. Secondly regarding what kinds of meet we see that Noah took 7 of every “clean” animal in the ark. What does this express? Obviously and simply that there were animals they ate and others they didn’t eat. More can be said but I will leave it at that. Mankind did eat meat from the beginning.