Some translations set each line of poetry farther to the right than the rest of the text to make it easier to read. The ULB does this with the poetry in 7:17, 21, which are words from the OT.
The high priest was normally from the tribe of Levi, but Jesus was from the ruling tribe, Judah. His right to be a priest came from the tradition of Melchizedek, who was a priest before the Levites came into existence. This passage will be difficult to understand if Genesis has not been translated first. (See: [[rc://en/ta/man/translate/figs-explicit]])