The main reason for the retraction was due to the research being unreproducible – The researchers had revisited their work after coming to the initial conclusion (that peptide was the reason RNA was able to copy itself without the presence of DNA. Later a member of the lab had tried reproducing the experiment, failed, and looked further into it to find that the peptide did not actually foster RNA as they had assumed in the initial experiment, and that the researches mistake was likely their belief in finding the answer without being thorough.
Yes, it could have been avoided – The mistake was largely due to excitement over the discovery and a lack of thorough investigation into the matter before publishing about it. The same lab found the mistake later on, and likely could have found it before releasing the paper if they had been more cautious about the discovery.
A retraction is when the paper id considered invalid as a source, often due to mistakes in the research (such as due to reproducibility of results), and generally withdrawn.
A correction is when mistakes have been made in the paper, but not ones which actually invalidate the research – mistakes which can be fixed without completely changing the results from the research.
I couldn’t find online sources which explained the definitions very clearly, so I’m not sure if they can overlap (eg, something was retracted when it could have been safely corrected), so I’m also not sure how accurate I’m being but it’s my guess based on the connotation of the words and the importance of research papers – They need to be accurate, so minor mistakes can be safely corrected to make the overall paper realistic, but if the mistakes are likely to change the conclusion or even demonstrate a flaw in the method, then it would have to be retracted as the entire research could be considered invalid. It doesn’t mean nothing in the paper was right, but it can mean a substantial flaw in the research ruined the integrity of the information enough to make it retractable instead of just correcting the mistake. An example of a correctable mistake would be something like misnaming, while retractable would be something like using a completely wrong compound or mistaking results (resulting in reproducibility).
https://retractionwatch.com/2018/03/16/caught-our-notice-voinnet-co-author-issues-another-correction/ this paper mentioned on the site had some corrections made in reference to images used on the paper which were duplicated/altered, for example.
https://retractionwatch.com/2015/04/01/you-cant-make-this-stuff-up-plagiarism-guideline-paper-retracted-for-plagiarism/ This paper by contast was retracted, due to the paper using plagerised work.