speratus said:

The whole of Romans 9 teaches justification by faith alone. Parts of Romans 9 teach election. Nothing in Romans 9 teaches reprobation being defined as God making a person a vessel of dishonor.

There is no justification mentioned in Romans 9

I agree that God created Adam knowing He would damn him and his seed. However, His purpose was the salvation of the elect.

There is a purpose in all of what God does speratus. Look at verse 11 and 12.

before they had yet been born or had done anything, good or bad, in order that God's elective plan might continue,
not by works but by his call--she was told, "The older shall serve the younger."
As it is written: "I loved Jacob but hated Esau."
Before they were even born.

Here is your answer, a verse that is overlooked:

What if God, wishing to show his wrath and make known his power, has endured with much patience the vessels of wrath made for destruction?

MADE FOR DESTRUCTION. They were MADE for this purpose

There never was a sinner half as big as Christ is as a Savior.