Minus the fact that Lavos needs the humans DNA so that it can evolve into the ultimate being on the planet. Without that DNA I doubt that the core can even function correctly. It also leads me to assume that the core is not made until much later with regards to the initial landing.
I see Lavos's attack on Zeal as a precautionary measure to prevent the humans from getting too powerful. Lavos knows that the magic it gave them made them tons more powerful, and once they figured out how to manipulate that magic into energy they were wasting the energy that Lavos needed to reproduce. Thus Lavos destryos Zeal, killing off almost all magic wielding humans and preventing them from using more of its energy in the process.
What do you base that upon? I believe that if Lavos survived an immeasurable journey across the vacuum of space, he can survive on a lush planet, abundant in resources. It's like introducing a predator into an ecosystem that has no natural defense against it, and even if he HAD killed off all humans, he would have still absorbed the useful DNA of the creatures in 65,000,000 B.C. He probably would have launched an attack on the rest of humanity, but a planetwide assault on all sentient life would, I believe, be beyond him.
Lavos is a parasite... sucks the energy of the planet and the lifeforms' DNA. People try to eliminate parasites, and parasites do not enjoy it, but if the human dies well the parasite is kind of screwed. You know, no more energy source for survival. Humans are the planet's immunity system against this massive parasite (very incomptent ones when you look at what happened to Zeal), but nonetheless they eventually rid the planet of this disease. Humans do not need Lavos, but Lavos needs an advanced lifeform, humans.
Lavos is a parasite on
the planet, not on humans; humans are in direct competition with lavos. In response to the point about humans being the planet's defense against invasion, I say this:
Humans may very well have evolved as a defense, if an inept one, and that is fine, but in the end it is irrelevant that they are. Lavos would attack them because of that standing, but more so because they are direct competition. when you look at it in this way, you are furthering my point that lavos WOULD destroy humanity, if given the chance. If I were lavos, I wouldnt worry about humans being there for any other reason other than competition, because the chance of them infilcting any hurt upon me would be so infinitesmally small as to be unnoticed. In the end, this was his downfall, but it was a string of unlikely co-incedences sixty-five million years long that lead to Lavos' destruction.
Lavos doesnt need humans any more than humans need him.
Lavos WANTS humans to suck the DNA from, but it isnt necessary. If he can survive crashing into the planet at more than terminal velocity, and the trip across vacuum and whatever other difficulties he faced whereever he came from, I believe he can survive the planet. Humans arent a factor for survival, for lavos.
You might say that he needs them to evolve the proper equipment to survive the atmosphere and environment of the planet, but he could get that from an ant, or a rabbit, just as well as he could from a human.
I appologise for my stilted rebuttal, but Im not feeling 100% today, and I cant think.