It’s probably too optimistic to assume that there is a single “great filter”. Instead, there are probably a series of filters, any one of which could end a line

It’s probably too optimistic to assume that there is a single “great filter”. Instead, there are probably a series of filters, any one of which could end a line that leads to an intelligent civilization that can reach into space. Think of them more as achievement levels in a video game. You might die on this level, but if you don’t and get to the next level, you have to avoid dying on that level, now.