Why is human excrement ickier than animal excrement

Humans evolved to be omnivores, so everything is fair game.
https://www.google.com/search?q=have+humans+always+been+omnivores&rlz=1C1ASVC_enUS940US940&oq=have+humans+always+been+omnivores&aqs=chrome…69i57.8632j0j4&sourceid=chrome&ie=UTF-8

That said, post meat eating poop is one of the smelliest: To digest foods high in sulphur such as meats, garlic, dairy, broccoli, kale and cabbage, your gut has to work overtime. This produces a lot of gas, which makes the poop smell bad. These foods, even if the digestion works fine, can make your poop smell bad.

Source: https://timesofindia.indiatimes.com/life-style/health-fitness/health-news/six-reasons-why-your-poop-smells-so-bad/photostory/71274090.cms?picid=71274110

Edit: Two of the three things you mentioned that may cause smelly poops is dairy, which people who are lactose intolerant like me have a problem digesting as mentioned in the article I linked above.