There are TONS of brand new players and returning players on P99. Green was a huge boon to the population. I can't tell you the number of people I've met in game who said they use to play back in the day and decided to finally try P99 due to green.
Please don't give up, P99/Classic Everquest is hard but very rewarding the further you get.
Levels 1-20 can be some of the hardest levels, Put your head down and push through. Send /tell to people and do /who level 5 10 to try and put together groups.
Don't get discouraged and check out the
https://wiki.project1999.com
ps. Rogue is a grouping class, Be aggresive about finding groups to join. Get on group lists for dps. Find out who the leader of the group is and ask them to add you to the DPS List.