What are the essentials of life though? Other than mere survival, I'd put my vote in for creativity, discovery, socialization, and critical thought. I see these as inseparable from technological progress. Humans are born tool-users and -makers. We will always want to answer the question "how can I make it better?" To that end, technology is the sum of all the things we do to improve on what we see. For the creative life, technology isn't an essential input - it's the inevitable output.

how many of us nowadays would survive if - God forbid - there were some catastrophic event that made technology functionless?

I think the risks we're diminishing - epidemics, malnutrition, the risks of childbirth, defending against other apex predators, deadly weather patterns - are better to put behind us, at the risk of being at least somewhat dependent on our technology. If the technology enables us to live longer lives more dedicated to the aforementioned creative impulses, it's a net gain.

we're also on an unhealthy path toward overpopulation (assuming we aren't already there). Natural selection is meant to occur and getting rid of it is us meddling into things that we shouldn't be meddling with.

For the sake of a good argument, I will posit that all problems are solvable through creative engineering. Solving overpopulation, for example, may be something we can figure out within this generation. Terraforming for space; improved farming techniques, or perhaps synthetic nutrition or a biotechnical metabolism that doesn't require as much of, or the same kind of foods to solve hunger; a stronger push towards green technology, or using bioelectromagnetism to exploit the energy of our bodies... if there's a problem, our minds can find the answer. It's up to our society to engineer the solution.