Well, you are good at speculating, and I appreciate most of what you said as speculation. Regardless of whether aliens started life here, it had to begin somewhere, which leaves the same question, did life begin by a magical process somewhere, on a rock floating in space, from material on the rock and from whatever could have come from the remnants of the BB in a rudimentary galaxy.
This is actually a good point. Life, or organic material, coming from the outside does not explain abiogenesis. It just shifts the problem to the next level.
I could also say that all complex atoms that make life come from the explosions of stars, while still explaining nothing in terms of how duplicating organisms, with such constituents, arose.
Ciao
- viole