To be honest, overpopulation is a problem for the reasons you mentioned above. If food is plentiful, then why is World Hunger still a thing? Why is it still hard for some people to get fresh, clean water? Resources are probably not as plentiful as you think.
World hunger, clean water and even finer things like economic opportunity are not universal, basically. You're missing the part that involves taking resources out of the ground and working them into a consumable state, which is literally all of the human effort that isn't happening in some places to make it happen. The reasons for why people aren't instinctually driven to work and provide for everybody across the board basic needs like that are innumerable, and very situational on several scales, from personal all the way to global. This is the practical reason why universal necessities have never been a thing.
We do know, most certainly, that it isn't happening, and we also know, most certainly, that there are way more than enough resources for us to survive with the 'burden' of a larger world population. 70% of the earth's surface is water, and if we really have to we have the technology to desalinate that water as needed to stay alive. The world's breadbasket is sitting right in North America, providing a huge agricultural contribution that we definitely couldn't subsist without. The veritable jungles of the Amazon, and places like Borneo and Papua provide a lot of cover for the carbon we emit, and we're making excellent progress on curbing that so we don't inadvertently destroy ourselves with pollution.
But that leads in well into the main point about resources: it's not their presence or lack thereof, but rather what we do with them and how we handle them. Nothing here exists in some suspended state, or vacuum where you can say there are X resources and Y people, and there's any amount of math you could write in your lifetime that adequately accounts for that and would be at all intelligible to laymen.
It's not just a matter of efficiency, but also sustainability. We want lumber, but we need a lot of trees to persist in the ecosystem. When you bring concerns of fossil fuels out of the town hall and into the real world, things become a lot harder to deal with because you can't just belly up all of the world's oil production at a moment's notice because it's bad. It
is bad, but it's not as simple as declaring it bad and expecting it to get its mess together. If you could actually stop all oil production tomorrow, it would cripple the world economy in a way that is unimaginable compared to past depressions. Such drastic things are a far graver, and much more predictable disaster than the hypothesis that overpopulation is going to destroy the earth, or our habitat or whatever. No, the planet will be fine, and the only way we'll be killing ourselves via habitat destruction is by taking poor care of the resources we have.