Needs more meat. I can’t critique what isn’t there!

Although, try italicizing the thumps.

Whoever “They” is is undefined, you should probably fix that.

The narrator is also pretty undefined, and at one point seems to be just an observer and the next omniscient. Perhaps make “They” wondering what the sound is.

Thump is a terrible noise for hooves, and thumpthumpthumpthumpthump just sounds like a guy trying to get out of a coffin to me

To be blunt, the whole “so random it’s funny” thing isn’t, never was, and never will be.

Focus on writing in a more natural voice and your prose will improve a great deal.