Only one can likely be credited as directly causal to a human extinction, but I’d think several factors can end up contributing to keeping us grounded even if we stick around for several additional millennia. And we could to some extent experience several of them simultaneously. For example if it is necessary to successfully create one or more technically possible (unbeknownst to us) technologies, but they remain unproven for the entirety of our species span of life on Earth. And while this is attempted, we end up with shortages that make soace exploration and colonization politically impossible, as the resources are never allocated for the purpose.

In this case we’d have both problems, but solving either one of them would still not get us out there.

In another example, perhaps even the technology is proven eventually, but due to scarcity rhe window of opportunity temporarily closes, and then wars, plagues, and a few other factors set humanity back to the stone age with a small population. Perhaps some predatory animals end up very successful at hunting us to extinction. Or perhaps we’re gradually finished off by several famines.

One could maybe point one cause out as more consequential than the others, but if the problems end up being such a quagmire I’d say they all played a part in filtering out humanity from interstellar colonization.