they had, but advanced mario people being how they are, they weren't gonna quit trying to beat it just because no human ever had.

Not the first TAS-approved level that people have beaten either. Bombs5 also uploaded thanks to tool-assist and also was cleared a year ago. GG to Sanyx for TtH and Fast for Bombs5. Trials of Death is another feat to be cleared at all, which was cleared RTA by its creator and about a month ago by jcthechampfogz .

SMW kaizo hacks also exist and not all creators clear their own hacks and lots of older hacks were intended to be cleared with savestates (but people choose to take the challenge of doing them without). Fruit dealer clear (first clear was by kezcade I believe, followed by lungfish, boothebun, and tjb0607; the last of which did all practice without savestates and defeated it 8 times in a row - a boss intended as TAS-only). There's also Hacker's Dream's last level, but I think its creator may have RTA beaten it themselves at least and intended it to be at the upper edge of human-viable.