According to Wikipedia, Uber was founded almost 3 years before Sidecar (March 2009 versus January 2012)... so Sidecar may have suffered a "timid-mover disadvantage", but not really a "first-mover disadvantage".
Uber was only black car back then. It is akin to a professional limo service. Sidecar was the first service that use regular cars. Lyft came afterwards.
Uber Black was 2010 - 2012. Than after Lyft properly launched their service Uber followed with the now more popular UberX.
UberX launched in early 2012, before Lyft. But Lyft, Sidecar and Uber were all likely developing their 'low cost uber' versions at around the same time. After how much success Uber had already had with just Black cars, the idea for a lower cost alternative was obvious enough that lots of companies jumped in.
Sure? IIRC Uber was hesitant to launch a 'ride sharing' product until Lyft did in SF. Any links to guide me?