There’s probably also a distance / lifespan filter: (4) That interplanetary colonization is possible (using relatively low-tech means) given the lifespan of th

There’s probably also a distance / lifespan filter: (4) That interplanetary colonization is possible (using relatively low-tech means) given the lifespan of the species and the distance to nearby habitable planets. For example, life could develop in a solar system with only 1 habitable planet and the next habitable solar system could be dozens or hundreds of light years away. Now you need to invent a fully self-sustaining long haul space craft, plus have the technology to pause death (or have the will to confine hundreds or thousands of generations to life on a space craft, plus have the ability to effectively pass down enough survival skill information from generation to generation that won’t use it, but will simply practice it in order to relay it).