What would be the purpose of sending a ship far far away for purposes
of colonization and even put genesis chamber inside it but then do not
include a codex so it would be useless?
Petitio principii is a poor mode of analysis. In the film, we aren't told whether Scout Ships contain codices. We aren't told a lot of specifications: from shields to sensors to atmospherics to self-repair to waste management to life support, etc. Asking the question assuming absence as answer is faulty reasoning. Instead, if your assumption causes an obvious error it's far more reasonable to challenge your assumption than proceed on it as premise.
We have plenty of clues that Scout Ships contain codices. They are scouts afterall- leading the charge- yet equipped with Genesis Chambers. This logically implies: 1) They were intended to start populations; 2) Before terraforming; & 3) Meaning only ALREADY HABITABLE environments were scouted and marked for terraforming (like turning Hoth into Endor; both habitable but one allows life to flourish more comfortably and easily).
World Engines were not sent to prepare the way for Genesis Chambers. Instead Scout Ships created populations to prepare the way for World Engines. This demanded that Scout Ships had a means of making Genesis Chambers viable, meaning an onboard Codex. Of course, if you don't accept the reasoning, we have explicit proof of this in the form of the Man of Steel prequel comic:
Is it a plot hole to cause Zod to need to capture Superman only?
Of course not. The film tells us that the Scout Ship is from Krypton's Great Age of Expansion, 20,000 years prior to to culture of contemporary present-day Krypton, and deeply divided philosophically. The order events is as follows, according to Jor-El:
- We built outposts on other planets...
- our civilization ﬂourished...
- Artificial population control was established.
- The outposts on space exploration were abandoned.
- We exhausted our natural resources.
That means that during the Age of Expansion, there wasn't eugenic determinism or a society built around or controlled by codices. It was when that agenda was introduced into the technology that society ordered itself around The Codex, purity, destiny, pre-programmed rigidity... and accordingly calcified and died, unable to change, adapt, or respond.
That is what Jor-El is fighting against and what Zod seeks to preserve.
If Zod could ignore his programming to innovate or tolerate in terms of Kryptonian society, he wouldn't need "THE Codex". He actually wouldn't even need any codex. He could have restarted the Kryptonian race through natural birth. But that was an abomination to him. He'd rather they go extinct than commit that heresy. He could have started a clone program or interbred with other races. Etc. None of these are viable alternatives to an inflexible pre-programmed person with a specific and absolute vision of Krypton held with conviction. It is completely within the story that Zod should desire THE Codex as opposed to any alternative.
we know that Kal-El has a copy of codex in himself. So it would be
possible to put a backup copy of codex into every Kryptonian
This is a poor criticism. Jor-El's bonding of the Codex to Kal-El was novel. Jor-El is the progenitor of several novel technologies: Phantom Drives, The Black Zero, non-Liquid Geo Holography, sentient AI, etc. What he did was new and unknown to other Kryptonians at the time, which is why Zod kept looking for a physical manifestation of the Codex, why it was a surprise it was found in Kal-El, and why he had to ask whether it could be recovered from a dead body (not knowing the parameters of a new technology). Asking why a novel technology has not been used all along is like asking why the Scout Ships didn't all have Phantom Drives. New tech is new.
Why would Kryptonians not make copies?
Again, how do you know there aren't copies? In fact, Zack Snyder explicitly says there are multiple copies of the Codex throughout the planet prior to its destruction during a Yahoo! Movies Blu-Ray Release event. Regardless, this is again an example of the product of poor analysis presuming a prejudicial precept- begging the question- instead of analyzing honestly. If it's not practicable for the entire population of a planet to come from a single point or if all of society is ordered around replicable data... it's unlikely to be restricted to one instance, so when there's nothing in the film to the contrary, why assume there's only one instance?