to select, to take, to carry
捎 centers on the act of picking something up and moving it: selecting an item, taking it, or carrying it away.
捎 combines the hand radical 扌 with 肖, which likely contributes the sound. The exact historical development of the meaning 'to select, take, carry' is uncertain.
The hand radical 扌 beside 肖 suggests a hand reaching out to select and take something. Imagine a hand picking a small, moon-like object (月) and carrying it away.
For ソウ, imagine a hand selecting a single soul (ソウ) from a crowd and carrying it off: soul -> ソウ, and the hand takes it.