Hi
wondering
I can see how you would come to this conclusion, however, I'm not so sure it's that cut and dry. Let me see if I can try and explain.
In Matt 5, where I think those passages are coming from (5 -7), Jesus starts by saying that he did not come to abolish the law, but rather to fulfill it. Abolish means to distort scripture from its intent. In other words, 5-7 are correct interpretations of those hot topics of the day when it came to scriptural interpretations. Kinda like homosexuality is the hot topic of today.
Now then, the two schools of thought were that of Shemie and Hillel. Hillel was progressive and Shemie conservative. When Jesus says, you have heard it said, he is simply referring to how specific laws were being interpreted by different teachers. He then fulfills the law by giving the correct interpretation. This was also lived out in his life.
Elsewhere in scripture, when Jesus is asked, what do you say, they are asking who's teaching does he side with. Generally he took Hillel side and expanded with the exception of divorce where he took Shemie.
All that being said, I think covenant theology covers your misunderstanding. On the night of his betrayal, he instituted not only the Lords Supper, but he brought in the new covenant in His blood.
This is the covenant spoken by Jerimiah in chapter 31, verse 31. Isaiah also talks about this new covenant.
When you read the book of Hebrews, it's all about why the new covenant is better than the old covenant. Hence, no more sacrifices were needed.
When we are baptized into Christ, we enter into that covenant just like the Israelites entered into the first covenant at Mt. Sinia.
Hope that helps.