It's been thousands of years since our ancestors domesticated animals and plants. Farmers and breeders have been producing more "useful" species long before biologists, but Darwin (1809-1882) published his On the Origin of Species as late as 1859. So how was it like before Darwin? How much did they know, and how much they didn't?
u/restricteddata addresses this here:
https://www.reddit.com/r/AskHistorians/comments/rjarvs/prior_to_darwin_would_people_have_had_some/
This is one of a number of items in a category that I always enjoy: things that SEEM so obvious to us, so simple that we can be taught them as children, that weren't obvious to people in the past.
On the one hand it is almost as simple as you may think to take note, and advantage, of heredity traits. Farmers and animal breeders have indeed done this for thousands of years. But evolution is another leap on top of that. Humans can (relatively) easily make hardier wheat and friendlier dogs, but they're still wheat and dogs. The idea that this process, occurring naturally over a timespan that's hard to comprehend even now, can produce all the different varieties of plant and animal life on earth, is not an idea easily arrived at from observing hereditary traits. The fact that different kinds of dogs are related isn't too hard to swallow, but that dogs are related to bears and seals, and even more distantly related to cats and lions, and all these animals were related to small weasels running around 6 million years ago, well, that's a bug jump from making your dogs have pointier ears.
The one thing I would add to my previous answer (which was about whether farmers and the like would have intuited evolution) is that there were evolutionary theories prior to Darwin. The most famous (and most taken seriously by educated people) was that of Jean-Baptiste Lamarck, who argued in the 18th century that species did change, and that this happened through the exercise of a sort of vital force, and that the changes made by a given animal in this way (either use or disuse) could be passed down to its offspring. So in Lamarckian evolution, if you never skipped leg day, your children would have buff legs as well — what we today call the inheritance of somatic characteristics.
Which is a pretty bold idea, and unlike a lot of earlier allusions to evolutionary ideas (e.g., Erasmus Darwin), actually tries to nail down a physical mechanism (however hand-wavy we might find vital forces today, they were considered a kind physical explanation at the time, not something supernatural). The learned community of scholars tore it to shreds, however, showing that the oldest animal remains they had available to them — mummified animals from Ancient Egypt — showed no serious change. And as I pointed out in my other answer, they still had no real conception of how old the planet and life and human activity was; as evidenced that they thought Ancient Egypt was about as old as you might get, a whopping 5,000 years or so back. (The idea of millions, much less billions, of years was not yet really out there.)
Still, it was a pretty popular idea, and has a commonsense appeal to it. Why shouldn't the exertions of an animal not go to its offspring? You have to really be educated in genetics to not find that attractive; it is clear that some kinds of somatic inheritance does occur... it's just that its usually about environment (e.g., the child of body-builders tends to be in an environment emphasizing physical fitness, and so is more fit than the child of TV slobs), or some very complex epigenetic stuff that even we don't really understand yet (gene regulation and so on).
So even though most learned folk regarded Lamarck as wrong, the ideas were still popularly circulating. One young Charles Darwin was very intrigued by them, to be sure, and when he came up with his own theory of evolution — one that was based on natural selection and not somatic inheritance — he had the example of Lamarck's undoing as one of the things motivating him to get it right, and to also not publish for decades while he tried to do so. Today we frame Darwinian evolution in terms of a hard, genetic heredity (with no somatic influences), but Darwin's own ideas about heredity had many Lamarckian elements to them that we tend to gloss over today.
Anyway — there is much more that could be said about pre-Darwinian evolutionary theories. Peter Bowler's Evolution: The History of an Idea is an excellent overview of them. I dwell on Lamarck just to give you a sense of what the "best" of these looked like, and the fact that these had direct influences on Darwin's ideas as well.