Ehhh, it’s not entirely off, more of a mischaracterization.

Most of poop is water, even when someone is constipated.

The non water part is a mix of food waste, dead bacteria, live bacteria, and undigestible matter (like microplastics).

The exact percentages of all that varies. Water, for example, ranges from about 60-75% in healthy feces. But with extreme constipation or diarrhea, it can go higher or lower.

The remaining matter is going to be roughly 25% bacterial, viral, or fungal. Of which, roughly half is going to be alive still.

The rest is stuff that we swallowed, and either can’t be digested, or wasn’t completely digested. Carbohydrates tend to be the lowest presence, as they digest the easiest. Then proteins, then fats. Fats are the hardest to digest of the three, and tend to be the majority of partially digested substances.

Fiber makes up the majority of the indigestible matter, with various man-made substances making up the rest of that category.

No two poops are the exact same though. Our gut is a living, active biome. Our digestive enzymes and acids break down food into component parts very effectively, but microbes, bacteria in particular, help along the way, breaking things down more, and that makes the components we need better able to be taken up by the intestines.

Research into the gut biome and how it can affect the rest of the body is in its infancy, even compared to research on the brain, which is a big mystery despite much longer efforts to understand it. Gut flora really wasn’t considered as a factor in overall health until widely until the last twenty years or so. But, it turns out to have influence on everything about our bodies. So, poop science is strangely cutting edge work right now.