Olympia okay so going off of only the actual original accounts (none of people who have been here forever but aren't on that account so you can't easily verify and link as the same person) the oldest I can find are people whose first game was July 30, 2008. I actually found two of my friends who were in different games on that same day. So jason_2_12 as has already been mentioned on here, and also kingjames13, but king literally made the account and left shortly after, and Jason has been around more consistently, so probably a better answer.
oh, add JamesM to the July 30 2008 group. This is fun haha, I'm just thinking of people who have appeared further left than me in games and checking their dates.
Oldest as in has been here the longest, not as in oldest in age.