IIRC, there were well over 20+ vaccines in the USA alone that were being developed. I dunno about other countries... it turned out that the mRNA (Pfizer / Moderna) and adenovirus (J&J / AstraZeneca) seem to have been the fastest at production.
Everyone who spent $Millions on other vaccines are still waiting for those tests to finish. Only if you were lucky enough to pick Pfizer / Moderna / AZ / J&J are you actually winning in the vaccine race right now. At this point, its looking like if you bet on the wrong vaccine, you lost your entire investment.
-------------
USA spent billions on building "all the above". We have millions of AZ-doses sitting on the shelves, waiting for final approval (final tests just finished this past week).
UK ordered 4-doses per person (when only 2-doses are needed, and even though its not known if children can safely take the vaccine yet). That's another reason why UK is so fast: they aggressively bought extra vaccines at an extreme rate. UK plans to either sell, or donate, those extra vaccines later on.
By buying so much extra vaccine, UK ensured that they are at the front of the line when it comes to vaccine supply from the various companies.