This looks like a fairly heavy infestation of aphids. The clustered gray/black insects along the stems and curled new growth are typical aphids, and the distorted leaves come from them sucking plant sap. See if the aphids are alive or dead…

The holes in some leaves may also indicate cabbage worms or flea beetles, but the aphids are the main issue here.

What you can do organically if aphids are alive: Blast with water. Use a strong spray from a hose, especially under leaves and in the curled centers. Repeat every 1–2 days for several rounds. Remove worst growth, The tightly curled tops are hardest to clean and often full of aphids. Prune and discard heavily infested parts.

Insecticidal soap. Very effective on aphids. Spray thoroughly, especially undersides and stem joints. Apply in evening or early morning to avoid leaf burn.

Can you eat it? Usually yes if you wash thoroughly and remove damaged leaves. The aphids themselves are not dangerous to people. However, the curled center growth in this photo is pretty heavily infested and stressed, so quality may be poor. I would trim aggressively, soak in salted water, rinse well, and cook rather than eat raw.

Good luck

Len