Well...we don't really know, but the odds are pretty good that this was probably a very important source of building block compounds. Some of the asteroidal material that has been recovered from meteorites is classified as 'carbonaceous chondritic' which means it is rich in organic molecules locked up in a mineral matrix. There seems to be a lot of this especially in the oldest recovered meteorites, so that means that during the ancient 'bombardment era' the Earth was indeed pelted with billions of tons of organic material. Comet nuclei also pelted the Earth and may have brought to the Earth much of its present-day water to supplement that which was outgassed by volcanic activity. But cometary material is cold and rich in organic compounds, which I believe is not the case for outgassed 'steam', so again it seems that the Earth was the benefactor of lots of organic material 'from above'.