Levels in which you don't have a rope, nor a vehicle have become exceedingly rare to find; if any are posted, they are immediately downvoted to obscurity due to difficulty.
I, however actually enjoy playing these crawling levels, and the only way I find the rare few is by typing in crawling to the search bar, finding the poorly made levels, and looking at the profiles of people whom completed the levels very quickly, and finding good crawling levels that would not be found otherwise.
The authors of non-rope, non vehicular levels are hard to find, and these are the only ones I have found (they have non-crawling levels too, just sort through them to find the crawl levels)
Stryker - Many hard crawling levels (some ear assault so turn sound low)
Sasuke Viet Nam - leetball, but you never go down a hill.You have to push yourself along and leap. armygamerofwar - Many very difficult crawling levels.
JackPotato21 - A few crawling levels, pretty easy.
iHateRadishes - Several crawling levels, varying in difficulty.
In the replies, please put more authors of crawling levels.I have a feeling that there are many more out there, and maybe I can find them with the help of you guys.