many
濈 is a rare kanji whose core idea is a large number or multitude, often associated with a crowd or abundant flow. Its standalone meaning is narrow and primarily literary.
濈 combines 氵 (water) with 戢, which likely contributes the sound and possibly the idea of gathering or collecting, suggesting a multitude of water droplets or a crowd. The exact historical development is uncertain.
Water 氵 plus the complex right side 戢, which looks like a crowd of elements (耳, 戈, 口) packed together. Picture a multitude of water droplets merging into a vast flow.
For シュウ, imagine a huge crowd of people all wearing the same shoe: shoe -> シュウ, and the multitude of shoes represents the kanji's meaning of 'many'.