What things were launched from early catapults?

Answer 1

Lots of stuff. Rocks toward castle walls, flaming bags of hay to set fire to structures within the walls, and even plague-ridden corpses to sicken everyone inside (famous way the Mongols spread the Black Plague to Europe)

Answer 2

The earliest form of catapult, which was invented by the Ancient Greeks, fired large arrows at the enemy. They were clumsy but scary enough to shatter the enemy morale. These were called Ballista. Later on this was upgraded to a Springald.

As catapults were developed more, they were designed to toss large rocks, which were used to batter down defences such as towers and gates. The first of these catapults were called Mangonels. There are stories that they were sometimes also used to propel dead bodies over the walls of the enemy castle (dead bodies carried disease and lowered morale).

In the medieval era, a more powerful catapult was invented, called the Onagar. This had a much longer range than the Mangonel and could fire a heavier load. The downside was that they were very heavy and difficult to move.

In the late medieval era, the catapults were advanced yet again to the scariest form of catapult known to man - the trebuchet.

The trebuchet had an amazingly long range, so projectiles could be fired from afar without risking the equipment being flanked and destroyed by defending cavalry. The trebuchet could fire large rocks, bundles of wooden and iron darts and even, deadliest of all, a jar full of flammable oil which was lit with fire and then hurled at the enemy, setting their defences and troops on fire.