You could ask me the same thing, I think.
Paul can bring us to more than what we understand by only seeing what Jeremiah 18 says. He is not only repeating what has already been said, but showing more.
And, again, I find it interesting how we all have been made "from the same lump".
And there is other scripture which I think can be included in the context. Jesus says that only God is good. So, to me it is theo-logical, that only God has the goodness to produce a good choice. So, only thanks to God has any evil person changed to choose what is good. And we all have been evil, according to what I see in Ephesians 2:1-3 which plainly says "we all" "were by nature children of wrath" > it was not our nature to make a right choice, then. And Romans 6:17 says the thanks is to God; the thanks is not to us!!!!
And my personal logic is that if we all came "from the same lump", how could one have the nature to make an evil choice, while another from the exact same lump and nature would have the nature to choose what is good? I understand, though, that this is just logic.
But I have shown I have various scripture as context.
Anyway . . . another thing > just my sort of scholarly logic, though, I admit > if God can be the Potter of a whole group of people, then He is being the Potter of each individual in that group, in order to have the sum total result of being the Potter for the group. It's kind of hard to effect a whole group, without personally effecting every individual in that group.
And God is personally relating with every human, in some way >
"God resists the proud,
.But gives grace to the humble,"
we have in James 4:6 and also in 1 Peter 5:5. And with this we have that "He has mercy on whom He wills, and whom He wills He hardens." (in Romans 9:18) This, I would say, supports that God personally deals with each person, as each one's personal Potter

. . . while, of course, there can be group effects which are the sum total to how God deals with individuals.