Zoro can be base human but this is one piece. Like swords can cut mountains realistically but somehow that is not an issue in one piece. Half melted human WB can put Akainu and destroy Marineford but normally he should be dead when his face was melted half. Only thing that got affected was his health and his stamina. Not his attack power. And Sanji broke his leg against Bergo but able to run in punk hazard without any treatment. Lightening should kill people or atleast burnt them but somehow so called base human Zoro was just fine.
Again stop comparing zoro to DF users, his strebgth comes solely out of his normal human body, if his body is heavily damaged he's left with nothing to compensate for it, will power can only carry him so far, at thrillaer bark he told kuma that his body won't respond to his will any longer.
We never saw anyone in one piece get as injured as zoro got on the rooftop, doflamingo got his insides torn up but he reconstructed it with his threads and compensated for that with his haki and DF even base luffy was outspeeding him, he regressed from being able to handle both luffy and law to getting outmatched by base luffy.
Perospero and aokiji can restore lost limbs with DF. Whitebeard was only carried by the gura gura fruit,his physical slash vs blackbeard did very low damage.