During Jesus’s time when he preached to thousands of people with his disciples how were people able to hear him? I mean at that time there were no microphones or speakers. How were people able to hear him considering many times he preached to thousands of people at once?
Learning to "project" is a skill. Additionally, when there are no PA systems, people learn where is a good place to speak, and where isn't.
Both the Greeks and Romans built amphitheaters for various purposes, and a hillside can be used as a natural amphitheater. With practice it isn't hard to address over 1,000 people -- the largest group I've ever spoken to without amplification was about 4,000 people.