The codex contains the DNA of the unborn kryptonians, but he stills needs an artificial womb to grow them. The ship contains one of these devices. You can see one when Jor-El steals the codex.

Since the ship was meant for colonisation purposes, it contains one of these "genesis chambers" that would allow to populate a newly krypto-formed planet.

It's having all the DNA of your people in a set of floppy disks and not having access to a reader.

The codex contains the DNA of the unborn kryptonians, but he stills needs an artificial womb to grow them. The ship contains one of these devices. You can see one in Krypton, in the chamber where Jor-El steals the codex.

The ship that Superman destroyed was originally meant for colonisation purposes, as such, it contains one of these "genesis chambers" that would allow to populate a newly krypto-formed planet.

It's having all the DNA of your people in a set of floppy disks and not having access to a reader.