Does art necessarily have to be beautiful? Can't it just be provoking? Although, this is a whole 'nother can of worms.
I seriously doubt that humanity would have progressed into civilization without the boon of agriculture. It's the only known source of food that could support any kind of sedentary society and large population.
Your evidence is positively laughable. 70,000 years ago? Agriculture is generally agreed to have originated about 10-12 thousand years ago (though some have speculated up to 20,000. After the Ice Age (Wurm) ended. Perhaps you're referring to the Toba catastrophe? That was a supervolcanic event that reduced the world human population to between 2000 and 10000 people. Do you realize that this was when humans were hunter-gatherers?
I'll give you this. Agriculture resulted in a vast loss of biodiversity as humanity artificially selected crops and domesticated animals to maximize yield, and that they were initially quite vulnerable. The death rate in initial agricultural societies was much higher than in hunter-gatherer societes, but this was vastly offset by massive birth rate, brought on by the sedentary lifestyle. A mother could have more than one infant in short periods, because they didn't have to carry the infants in nomadic lifestyle which restricted their birth rate to perhaps 1 every 4 years.
But agriculture produced surplus food, and allowed people to specialize and develop talents in art, pottery, textiles, etc. Many of the things you value are products of this opportunity to specialize that stems of sedentary agricultural life. Hunter-gatherers had to spend the majority of their time simply procuring food. The hunters had an unreliable income, as the hunt was very liable to failure, and the simple changes of migratory patterns could leave a tribe without meat for years. The more reliable gathering created the bulk of their intake, but it was not as readily available, it didn't taste as good, and it was mostly low in nutritional values compared to the later agricultural stock as they'd been selected for yield, taste, and fill.