ancestor, pioneer, founder
祖 centers on the origin of a lineage or tradition: an ancestor, a pioneer, or a founder who starts something that others follow.
祖 combines 示 (altar, religious ceremony) with 且, which likely contributes the sound and may represent a shelf or ancestor tablet, together suggesting ancestral rites.
The left side 示 suggests a ritual altar, and the right side 且 looks like a shelf holding ancestral tablets. Picture an altar with shelves of ancestor memorials: 祖 means ancestor or founder.
For ソ, imagine a pioneer sewing the first flag of a new clan: sew -> ソ, and the founder starts the lineage.
—
grandfather
grandmother
ancestor; forefather; foremother
originator; pioneer; inventor; founder
homeland; motherland; fatherland; native country
ancestor
grandfather
grandparents
grandmother
ancestor; forefather; progenitor
founder of a religious sect
Mazu (Chinese goddess of the sea)
founder; originator; pioneer
(sect) founder; apostle; originator; inventor
ancestors
old people
great-grandmother; great-grandma
great-grandfather; great-granddad; great-grandad
founder of a sect
ancestor worshipped as a deity