Life begets life. We need to consume life to live. Be that plant or animal life (or algae or fungus) in order to survive.
Disney had it right in the 1994 clasic "The Lion King". They called it the "circle of life".
So, as an apex preditor (at least in groups), there is a limit to what the planet can provide to support our population. We can tweak things, like gaining calories from lower in the food chain (no meats or eggs or fish, just carefully chosen plants - oops, GM algae to maximize things), or choose, as a species, to "live" instead of just survive. That directly implies we choose, as a species, to have a smaller population than the carrying capacity of our planet.
So lets presume we are actually smart enough to realize that and do something to control our population. The next question becomes "What can we do to maximize food production of desirable foods?".
Modern industrial agriculture has a few problems: 1) Its heavily dependant on artificial fertilizers 2) Its heavily dependant on diesel fuel to run the equipment. 3) It degrades soil, using it primarily as a sponge for the artificial fertilizers 4) Insect pressure is increased by the tendency to mono-crop. ref: https://www.scientificamerican.com/article/3-big-myths-about-modern-agriculture1/ (https://www.scientificamerican.com/article/3-big-myths-about-modern-agriculture1/)
Brief history lesson: Farmers use to plant three main crops in the USA in rotation: Corn, wheat, and soybean. ref: https://extension.sdstate.edu/benefits-wheat-corn-soybean-rotation (https://extension.sdstate.edu/benefits-wheat-corn-soybean-rotation)
Corn root and ear worms destroy a lot of a yield. By planting in a three year rotation, those corn specific worms that overwinter starve in the following years. But wheat is not particularly profitable, so farmer switched to a two year rotation of corn and soybeans. The soybeans help fix nitrogen, which reduces the need to artifical nitrogen (anydrous ammonia), and thus reduces production cost. Soybeans are also rather profitable to plant, just not as profitable as corn. The worms have evolved, and now can lay dormant in a soybean field for a year until the corn comes back. Whats worse, many farmers have taken to JUST planting corn - year-after-year - until the insect problem is to bad the cost of control exceeds the profit difference vs. soybeans.
The "myths" articial points out another fact: Something like 90% of the USA's excess food production is NOT going to starving countries, but to other developed nations simply as a cheap food source. I personaly found that interesting.
So.. what are the problems when we look at the situation over a timeline of hundres or thousands of years?
1) We are destroying, not building, our soil base. Rome fell for similar reasons.
2) We are dependant on non-renewable resources (oil, phosphate bearing rocks, etc.)
Solution: (mind shift required) Stop farming for maximum profit, start farming for sustainability. Soil health needs to be priority #1. Stablize the worlds population to the levels of food that can be grown using sustainable techniques. Maybe get back to a larger percentage of the "developed" world who are directly associated with farming. That is easily accomplished - we did it in the USA in WWII with the concept of "victory gardens". Campaign to have people in developed nations plant small plots of food - perhaps a few raised beds of peppers, tomatoes, squash, onions, garlic, herbs, etc. per family. City dwellers can use potted plants on porches and roof tops.
I think it sounds good in principle, but we need to dig further <pun intended>: We need to realize its all zero sum. You can't take humus from a forest without damaging that forest. I buy hay from neighbors for my cattle and feel guilty because I'm trading them short term profit for nutients from their farmland - and I know they don't replace those nutients, they just hay year-after-year and comment on how poor the harvest is vs. what they use to get.
There are VERY few natually recycled products in our world. Rain comes to mind. O2 <--> CO2 via plant growth, death, and decay. Over millions of years, rock as the earths crust shifts - but that does Humans little good. Everything from oil to rock based fertilizers is in limited quantities. We need to learn to deal with that and learn to recycle EVERYTHING, even if its cheaper to landfill it.