wow! That looks ROUGH! How big of a pour was it? How many guys placing and finishing?
I agree with some of the previous posts, a grinder will get the high spots out but won't do much for the low spots. Some self leveling may help with the low spots but feathering it so you will not notice under an epoxy coat will be tough.
I was worried about the opposite with my floor, I wanted level first, smooth secondary. That's tough mate, you gotta work with what you got I suppose and I know it isn't what you want to hear, but may be best to bust er out and try again.
I feel bad for you, that really *****. Of all the parts of my build, pouring my concrete made me the most nervous. Seems if anything can go wrong it will when it comes to concrete.