> other life in the solar system (which seems like a pretty hard "no" to me as a lay person),

There’s so much we don’t know about the solar system, little bacteria crawling around deep under the crust of a moon or swirling about in a gassy giant doesn’t seem too far fetched.

Wormy fishy creatures (or even more complex than that) under the ice of Europa is a bit more of a stretch, but even then I don’t think we’re aware of anything that would outright refute that possibility as of now.