where did we come from? The explanation I can piece together through memory is that we most likely come from organic matter that (though processes that are not yet well understood) formed the basis for cellular life. Random mutation and natural selection over hundreds of millions of years led to the speciation that includes homo sapiens.

I'm not sure that finding life on another planet would change the science much. Maybe there would be some connection, maybe not - they could be parallel processes, or maybe some kind of seeding function took place.

Either way, it would still be immensely satisfying discovery, one of the greatest ever.