Listing the descendants of Jacob, a general pattern emerges. “The sons of a were b, c and d”. Replace a with a name of one of Jacob’s sons and the other letters with names of Jacob’s grandsons.
Sometimes this pattern is broken by a female: announcing the name of Jacob’s daughter (Dinah), or granddaughter (Serah).
Our verse breaks the pattern in a different way. “The sons of Dan were Chushim”. How many sons did Dan have? Were they all called Chushim? Rabbi Jacob ben Asher (the Ba’al Haturim) translates Chushim as “bundle” (following Baba Batra 143b). Imagine a bundle of reeds tied at one end, branching out into many, at its loose end. So too, Dan only had one son but that one son branched out. He had a great many descendants.
By the time a census was taken (Numbers 1:39), Chushim’s progeny had multiplied into the second biggest of the tribes. Dan’s only son was called Chushim, but Chushim carried within him such potential, that he deserved to be spoken of in the plural.
According to the Targum Pseudo-Jonathan, Chushim isn’t a name at all. According to him, the verse reads, “The children of Dan were a numberless multitude of armed traders.” Dan had a multitude of children. Chushim describes them. Why weren’t their names individually listed? Perhaps because unworthy, and each indistinguishable from the next, they didn’t deserve individual mention.
How can one person be like many? You can be like the Chushim of Pseudo-Jonathan and merge into the numberless multitude of mediocrity. One into many. Alternatively, like the Chushim of the Ba’al Haturim, you can carry such potential, accrue such merit, and pack such a punch that you end up more like many people than one.