Removed them all, tried again. Same issue. Darn.
Might bite the bullet and just delete the theme. I have an export of it, but the whole gamble is hoping it’ll let me even re-import it.
Oddly enough, if I upload a .zip of an export I have from yesterday, it imports fine…but I’ve changed a looot since yesterday on it. If I then take that .zip that is importing fine, extract it, copy the updated files to it, re-.zip it, and upload, it gives 500 Error.
EDIT: Deleting the theme and re-importing the most updated one did in fact still NOT work…thank God I had a backup at least from yesterday. Now what?..