In the beginning, (the chaos time) there were countless objects finding their way to all planets, not just Jupiter. It still happens today. I understand the size of Jupiter and i'ts gravity would have attracted many of them from hitting us, but at any given moment, Earth was bombarded by comets directly, bringing with it....Ice....and the very beginnings of life to a sterile planet. I believe a great amount of earths water came from that ice.
Where did this life come from? Well, there are systems much older than ours, and the breakup of those systems could have seeded the younger one's like ours. In time, we will be the seed bearers of others. Where did life first start? We will never know for sure until we can prove if it can be started with a chemical or electrical nature.
Just my thinking of course....and what a great place this is....