Δεν ξέρω ακόμα και γιατί είμαι εδώ.

Why is “και” necessary here?

English Translation

I don’t even know why I’m here.

The AI explanation is misleading. Only the entire expression ακόμα/ακόμη και means even.

Ακόμα κι εσύ Βρούτε; = Even you, Brutus?