If you squat on the ground to shit very little is left behind especially if you eat a more meat based diet with less plant material. Yes, I have thought about this before and as I often work outside miles from the nearest privy I have made direct observations. P.S. I always stuff a pocket with suitable material and carry hand sanitizer because shit happens.

In Colonial, and Early America, corncobs were used for that purpose. The Chinese are believed to have invented toilet paper in the 6th century A.D.. Modern, rolled toilet paper was patented in 1883.

The ancient Romans used sponges on sticks, which they then cleaned by dipping them in salt water. Unfortunately they often used the same salt water more than once!

Well after I stopped laughing I found it a most curious question
I prefer the soft and durable tissue and care not to have been alive any time before Cottonelle tissue and Tampax feminine hygiene products. This could go in a whole crazy ass direction. Boy now I am thinking of a few other products I'm glad we discovered

Certainly a really interesting question and some really interesting answers too. No problem with posting it, good post.

We did like the bears, n wiped our butts on trees!

Little fur to protect anus

We don't have a tail to do it for us .

Beer and nachos. Wild goats don't eat those.

Well considering that for humans to have been 'designed' in the first place implies that there must have been a Great and Intelligent Designer involved then I perceive that you are possibly thinking that there may have been a 'God-like' hand in the matter somewhere.
However, since humans arose from much earlier ancestral hominid species, early ape-like species in particular, who were actually quadrupedal ( walking on all fours) the musculature of the buttocks, the Glutei, were relatively small and not protrusive ergo, passing faeces meant simply that the waste would be expelled mostly without contacting the surrounding skin or hair/fur.
Once the earlier Homids started to stand erect and become bipedal the Glutei then become more and more involved with the act of bipedal locomotion and thus grew larger, expanding to what we have today, i.e butt/arse cheeks, that need to be spread apart to facilitate defecation.
With early hominids body odours, etc, would have been the 'norm' and not overly noticeable since everyone would have smelled the same, but as we, Homo Sapiens become more communal and self-aware we would have begun to notice these things, found them somewhat offensive and, voila, in comes the necessity for removing any waste matter trapped in the residual hair around the anus.
Therefore, hygiene would have arrived and arse wiping after defecation rather than wandering with shit dags dangling from ones arse attracting flies, etc, and using available chunks of greenery, leaves, etc, would have the primary solution UNTIL some very bright spark came along and discovered that using softer materials such as sponges, bits of old cloth/skins,etc was better than greenery until actual paper was invented.
Evolution does NOT seem to plan or design, it merely takes advantage of an adaption/mutation that gives a significant advantage to one individual/s over the rest and that becomes the next norm and the beat goes on and on until the next advantageous adaption/mutation comes along.
I have also often wondered myself, HOW did the earliest female humans cope with the regular 'flows' of menstrual fluids and the waste blood, etc, from after giving birth before such things as Sanitary Napkins, etc, were invented.

Over tens of millennia, we evolved as predominately vegetarian animals. We ate our plants raw too. This diet is not nearlly as messy and odoriferous as the results of a meat and sugar diet. Try it!

Life has been shitting since day 1..