collect
僎 centers on gathering or bringing things together: to collect. The meaning is narrow and the kanji is rare, so treat its usage as limited to this idea of collection.
僎 combines 亻 (person) with 巽, which likely contributes the sound and may relate to selecting or arranging. The exact historical development is uncertain.
A person 亻 beside 巽, which looks like a complex arrangement of items. Imagine someone carefully collecting and arranging scattered objects into one place.
For セン, picture a person collecting one thousand (千, せん) small items: 千 -> セン, and the person gathers them all.