Greetings from founder Ronald Smit  

The founder of RSgallery2 is normally not reachable.
In January of 2019 surprisingly he left following message in RSGallery2 forum. 

Hi guys,
It is great to see the work I started over 15 years ago is still alive.  
I had a great time building the original RSGallery so to I did not expect to find this project, nor that my account would still be accessible!
I just wanted to say hi and good luck on  further developing RSGallery2!
Cheers,
Ronald 

Link to message in http://www.forum.rsgallery2.org

So it's definitely true that everything started in 2003, and yet it can be expected that 2001 can be a valid first launch date