AZ and J&J don't look useless against serious disease. They do look useless against infection, unless you get a mRNA booster in which case the combination looks really good against infection or disease.
Pfizer/Moderna are weaker than were against infection but still having an impact for months after dose 2, but they look ok against Omicron infection once boosted.
Past infection is less predictable, it may protect against infection for a few months in some. It may protect against severe infection for longer.