Thanks everyone for all your help and advice. Turns out I did have the right tool, and all it needed was some elbow grease

I sprayed it with WD40 last night, still couldn't get it out, tried it again today, and threading the handle with the center bolt was a bit easier, got some resistance, but it was easier to keep turning, and the crank popped off

Chainrings are changed, and the chain is no longer skipping (bent/broken teeth on the old chainring). Thanks so much for all the advice!