Where does “you” come from?

you (Old Leonese) comes from Vulgar Latin eo, from Latin egō, from Proto-Italic egō, from Proto-Indo-European éǵh₂ — I.

Ancestry of “you”, step by step

Step	Language	Word	Meaning
1	Vulgar Latin	eo	I go, I move; I advance, I proceed, I progress; I...
2	Latin	egō	—
3	Proto-Italic	egō	I
4	Proto-Indo-European	éǵh₂	I

you — Etymology, Origin & Word History | Etymology Explorer