TBS runs the show (at minimum) 5 days a week, usually in blocks. If you time it right you can catch the pilot. It's also on Amazon, but apparently not included in Prime.
This is how it all started ...
Leonard sure was thin in the first episode. Look at the pants Sheldons wearing .LOL!
Sheldon also had normal human sexual urges in the pilot. Leonard makes a couple of references to Sheldon's sexuality--okay one was a masturbation joke but still. Interesting how his character developed.
For the record, "groundbreaking comedy" refers to sit-coms that do something truly different. It changes over time because the envelope continues to be pushed. All the Family (originally a British show) discussed issues that had never been portrayed on television before, MASH did something similar, Seinfeld broke the mold of needing moral and family value lessons, Married with Children was the anti-sitcom--etc. Contemporary shows like Modern Family or TBBT while having slightly different set ups than other sitcoms still have the same loving, family dynamic that has been portrayed many times previously. And don't bring out the firing squad because I do enjoy both shows.
Also, I don't care about the OPs original threads. Why care so much to bring that up here? Pubert and I have disagreed a few times in previous conversations but shouldn't we treat discussions on their own merits? And this is a fun discussion.
Yeah I noticed that in the pilot. He actually seemed attracted to Penny especially after she said she like his board.

I also like that as the series goes on the friends especially Penny and Amy are affecting Sheldon. When Amy kissed Sheldon for the first time he just said a Spock like 'Fascinating". His Dungeons and Dragons tryst with Amy was also hilarious.