Actually, as someone who used to study anthropology (albeit a very long time ago), I think it is generally accepted by now that the ability to Carry Containers Of Stuff is generally agreed to be one of the real tool-using leaps in human development, perhaps as important as fire. I mean, you'll get the impression that people studying early humans are basically spearhead experts, but that's just because spearheads don't decay. (And because for a long time people assumed that hunting was The Most Important Thing, which has a fascinating intersection with implicit bias and sexism and stuff, and yes I am still bitter at things like 2001 for popularizing the idea that the most important part of human evolution was the ability to bash the shit out of a thing/animal/person, but that's a whole other story.)
If you can put meat in a bag, you can carry more meat. If you can put something like nuts in a bag, then nuts abruptly become a food that you can bring back to the tribe or save for later and not a food that you're required to eat on the spot because they are tiresome and stupid to carry by hand. In both cases your ability to feed yourself and your tribe just got a whole fuck of a lot better.
If you can put your baby in a bag, you now have both your hands free to stick a spear into things, pick nuts, fish, dig tasty cicadas out of the ground, etc. Your ability to feed yourself and your tribe just got a whole fuck of a lot better, and so did your ability to defend yourself while you do it. (And let's face it, your babies were already getting downright ridiculous in terms of the time it takes them to be fully walking-ready, due to brain size and being essentially premature; inventing Multitasking With Baby is like, pure survival at this point, and your way to do that is to create a specialized bag.)
If you can put water in a bag (first water containers very well may have been animal bladders or stomachs, not pots) you can bring water to your sick tribe members and they have a much higher chance of recovering.
And then you have elaborations of the basic "thing that contains objects" idea. If you make an exceptionally loosely woven bag and put it in the water, you can on occasion finesse some fish into it. And then you have delicious fish. If you put yourself in a loose and flexible bag of animal skin, your tribe can operate in the cold better, which changes your entire migration pattern and opens up new environments to you. If you make a hard container and fill it with water and put it over your fire, you have invented a new type of cooking that unlocks whole new food types, such as vegetables that need softening in order for humans to eat them. (Of course at the same time your stomach is becoming steadily more dependent on being able to fuck with your food in this way, but that isn't necessarily a bad thing, because the less energy you spend on digestion, the more energy you have to spend on other things, like brains. And big brains are good for unlocking whole new levels of communication, allowing for fantastic new levels of foraging cooperation, passing knowledge through generations, mate selection, and even various sorts of mental recreation where you imagine something that you don't see, and then convey that to your fellow beings.)
Bags are important, is what I'm saying.
