I think life in the universe was most definitely inevitable. The universe is too big for there not to be life. That's why I don't get creationists objecting to the improbability of life. It's extremely probable, considering the billions and billions of galaxies with billions and billions of stars and planets. I'm not sure about it being inevitable for earth though
I once wondered if life itself is part of some broader process of the universe that we can't really understand. This isn't to say that "humans" are inevitable (and for the record, I'm quite atheist) or that we itself are the purpose, just that there is some greater purpose for our existence down the line, given this direction toward increasing complexity as the article noted. Of course the purpose itself could be a very boring one. I mean, I doubt that an individual brain cell of mine truly cares about my stress at work.
I believe that it was a combination of the two. Evolution was always going to happen to animals. When humans started consuming more protein, we inadvertently started to enlarge our brains in a sense. Which could be considered luck.
I'm with you there, I see it as inevitable that something sentient and intelligent would evolve on this planet, it's luck that it was humans.