There is no good and evil. There is only economics. Anything that is not a Nash balance WILL die. Including any definition of good that does not meet the bar. Which is I think where your problem is. Evolution provides one definition of "good" and we live in a world that enforces that definition. I know people take offence at this and think Jesus overrides that. The truth is that what Jesus provides is a slightly different way of living together, and that way has proven it's success over what evolution would probably call a very short period so far. To apply the previous reasoning, does "Jesus" meet the bar ? I'd say the current situation is that evolution doesn't know, but is interested to see how things progress from here.

The whole point of evolution is that it does not "choose" the best path forward. It tries 9999999999999999999... paths forward (and "fighting" evolution is certainly one such path it is not -at all- opposed to try, just not with "too" many resources) and then kills of all but the, call it 100, best. In reality this force is very much active in today's society, as over 96% of humanity descends from less than 10% of the society that existed 2 generations ago. I would bet that this is a wholly unremarkable value for that has remained pretty constant over history.

This happens in phases. First you create a million experiments. Stir for a while. Then a disaster happens, and most of the experiments die off. GOTO 10. Obviously we are currently close to the end of the "create a million experiments" phase. Loads and loads of things are being "invested" in by evolution. That will stop at some point.

As to why humans live in (small) groups (meaning up to 50 people, no more), simple : redundancy, size, and efficiency. A natural human society is a group of 20-50 individuals (that don't behave all that individual, or let their colleagues do that either). The group has men and women, men being useful and expendable appendages that can be sent out to do useful things, like hunting, or fighting a neighbouring tribe when their location threatens to make the hunting grounds too small. Women that take care of progeny, and are not expendable (because loss of a woman impacts the reproductive speed of a group in a way that loss of a man doesn't, which in the short term can lead to losing a war to a bigger tribe, and the death that follows), and do whatever needs doing in a protected environment. To some extent, the bodies and brains of both kinds of humans have adapted to these roles. Not a very great extent, but it's there. It's nowhere near as specialized as you find in bees, spiders, or bacteria, and more specialized than you'd find in birds or reptiles. I would argue it's pretty similar to the sex differences you see in most mammals.

It is a useful way of organising, that you will find all over nature. There are bacteria that do this (even sexual ones, yes, they do exist, though they tend to be able to switch sex when convenient), there are loads of insects that do this, again you have loads of different forms, from monogamy to hives (with a single woman per society), there are lots of animals that do this ... I don't see the mystery here, I also see serious indications that while all of these forms of living together are obviously superior to solitary lifestyles. There are considerations though : if the hunting/foraging grounds have a certain minimum richness that is, meaning living together clearly makes more sense with what you'd probably term a "better economy", and larger societies need larger, denser economies, but they are also more efficient if such an economy is possible. Below a certain productivity value, solitary lifestyles are the norm (although that tends to be the end of the road for a species).

But the short answer is : why do we have societies ? For the same reason dinosaurs got big : because bigger lifeforms are more efficient. Dinosaurs were a mostly failed experiment in making the individuals bigger to give them economies of scale, without requiring groups, without requiring investment in a brain. Humans working together, or even competing, is a lot more cooperative than some lower lifeforms that we still call multicellular, and a lot more efficient than solitary lifestyles.

So does evolution "decide" the best path forward ? No ! You should. In the same sense that you should be a freelancer and launch your own company, meaning the caveat simply is : you will most likely crash and burn, and die/live in poverty.

TLDR: One human couldn't possibly live of 1 acre of land, but 10 acres will feed 10 people, easily.