All well and good in theory. The real question is not ‘can we?’, It’s ‘will we?’ Experience says ‘no, we will not.’ Few of us are willing to alter our lifestyles sufficiently to enable the changes you posit. Furthermore, at least half the current human population aspires to the same lifestyle the other half enjoys. That is something else that is unachievable. Famine, disease and war are the things that, in the past, held back the exponential growth in population. We have gone a long way towards ending the first two and, as you say, could go a lot further. But we have not succeeded in any meaningful way with the third, whch continues, driven by the desire I referred to above — of the poor to acquire a share of what the rich have and of the rich to hold on to it.
It happens with all species. I repeat, why supose that humankind is different? We have intelligence, I grant you. Do we use it wisely? I used to think so. Six decades of adulthood have taught me otherwise.