Cannot open existing/create new worlds

My minecraft auto-updated to version 1.16.220 and now I cannot open my saved world (I get the attached error the first attempt and then no response on further attempts) or create a new one (pressing the create button does nothing) so I have no ability to play at all.

I am on 64-bit, only have one world, had no issues in the 3 weeks since I bought minecraft and only play on one device.