Nobody has ever suggested that "fitness" in context of biology means anything close to the colloquial definition. Except perhaps @cladking.
I fear to ask but what colloquial definition is that. I wager my dictionary has dozens of definition and I won't get a straight answer.
As I've explained many times every individual is different. These differences are exactly as complex as each of their genes and their individual experience because these differences "all" affect consciousness. Nature sometimes generates defective individuals through happenstance and these aren't really relevant because for the main part they are just food for other plants and animals which cooperate to maximize the efficiency of their destruction. Of those who are not defective each is more likely to survive under different conditions and different sets of events. But defining this difference as "fitness" is simply ignoring the fact that they are each capable of surviving and procreating in the real world or they wouldn't have the genes they do. They wouldn't even think the way they do if they were another species. Toads don't act like birds and if they tried they'd be eaten almost immediately; very very efficiently. It's very easy to predict which toads will act like birds because none will but it's wholly impossible to predict which toad will prosper in any given environment and it's impossible to predict what traits will be passed down by toad-kind. The cart is placed before the horse. Reproductive success is just as unpredictable as which traits will facilitate it and all those toads that are off spring from the most successful are still just toads and the exact same species as their parents. At least they would be the same species if there were such a thing so it's better to think of them as individuals who are as different from their parents as they are from one another.
Speciation actually occurs when toads that act a lot like frogs are the only individuals that survive a bottleneck. They act this way because of consciousness and peculiar genes that underlie it. All these "toad-frogs" get together and voila in a short time what ya' got is a brand new species.
Nature is always experimenting (unlike Evolutionists) and comes up with mutations, hybrids, and whatnot. Some of these, like Adam's ability to consciously manipulate language proved highly beneficial in a social species that already succeeded through cooperation.
Peoples ability to believe they know everything has been absolute since the "tower of babel".
Homo omnisciencis. Our species has been lecturing anyone who will listen for 4000 years. We don't even need to listen to other people because they are salad tossing worms until they agree with us for the same reasons to every decimal point.