Artillery was volleys of javelins, arrows, slings stones, etc. I am not an expert either but, Ballistas were also thing at this time. I think they were called Oxybeles and Gastrophetes?
However, it is not clear how widespread these larger weapons were as most accounts do not talk about them too much. They focus on ramming and boarding instead. You know, Heavy Infantry Uber Alles, that is the ancient Western way!