A caveman suddenly appearing in a modern city

Imagine a caveman from 100,000 BC suddenly being transported in time to today and placed for a brief time into the middle of a modern city. A cacophony of noise; a staggering number of people all seemingly very busy walking in random directions all ignoring each other; the movement of large inanimate objects moving under their own volition, some of which travel at an unbelievable speed. Completely and totally frenetic.

Then he suddenly gets transported back. How does he explain his experience to his fellow cavemen? It was very busy, strange, noisy, lots of people? That scarcely conveys it. Nor would my description above convey what it was like. Nothing could, it's simply completely outside anything they have ever experienced. Any attempt at a description could not possibly convey the raw experience of being there.

Likewise for those who have had psychedelic or mystical experiences or NDEs trying to explain their experiences to us. Not that I've ever had any of these experiences.