As an 'experienced' Creative1 player, I think I got an answer. Roleplays. lol I think that people from c2/c3 eventually moved to Creative1 because of the mass amount of roleplays, and plus, when peeps join-roleplays are the "thing to do". And, C1 has a ton of them.
Back around early 2015, it was actually Creative 2 that was filled up to the max due to the roleplays. I guess people were bored and went to c1 to remake new ones or something idk.
creative1 has always been the most popular creative server (i think, at least. it has while i've been here.) i dont know why the other servers are so dead tbh. probably because of roleplays, and people leaving the other servers to play on creative1 because theres more people? idk.
In comparison its like C1: Some really sweet place to be at C2: Some alright place to be at C3: Just as shit as India [IMO, I despise India though I was born there but meh I just dont like it there ( ͡° ͜ʖ ͡°) ]