Hi Platypus, One of the arguments against the instantaneous creation of most of these eukaryotic organisms 4.5 billion years ago is that at that time, there was not atmospheric dioxygen (O2). The geological record is fairly clear that dioxygen didn't appear until ~2 billion years ago, based on the presence of detrital pyrite and uranitite, sulfur isotopes, and banded iron formations (among others that I'm forgetting). So those critters would have had a pretty rough time breathing.
Also, the formation of the Moon occurred about 4.4 billion years ago, and it's believed that the surface of the Earth became liquified magma at that time due to the huge impact that formed the moon.
Hi again, The difficulty with breathing something else instead of O2 is that it needs to be an electron acceptor. O2 is one of the best electron receivers out there. Other anaerobic organisms use things like methane, hydrogen sulfide, and some more obscure transition metals. However, among eukaryotes, O2 is the universal electron acceptor.
O2 is not stable and it is continuously replenished by photosynthesis. On planets without life, there is no O2 in the atmosphere. On Earth O2 it is believed that O2 originated as a waste product from photosynthesis. So O2 did indeed originate with the first plant-like organisms (in this case, photosynthetic bacteria).
Still, if we move the creation back to 2 Ga (billion years), we still have to make the O2. So maybe the first bacteria and archaea were created ~4 Ga, and then these other creatures were created 2 Ga. Other than conflicting with the fossil record (and not being the most elegant of theories), it wouldn't be that bad an idea.
Do you know of Louis Agassiz? Agassiz was one of the last geologists/zoologists to resist the Darwin's theory of evolution. His idea for the succession of fossils amounted to the spontaneous creation of each and every species of organism. You proposal is a bit of a mix between Agassiz and Darwin :).