1.
The real factor is that a Human male and female will parent a child with more attention, care and understanding than any other animal, and for relatively longer. Not just spending time together, but performing parenting tasks. Humans arguably do the most parenting of any other animal.
You learn everything from your parents. Most animals learn the basics only, and learn the rest from the wild. That's because Humans are good at parenting, and have been selected by evolution to be great parents to give their children the best advantage. When two people make love (in nature), ultimately, it's to become great parents and raise a child from ignorance to self-sufficiency (which is more difficult for humans, because they learn SO much more than any animal). Think about it like science: We build on the discoveries of previous scientists. Similarly, we learn and grow based on the tuition of our parents. This is an evolutionary strategy to confer many benefits to human beings. This is how we are able to know so much (compared to animals).
For Humans, parenting is in-depth and a long term commitment (for the species as a whole, not only individuals) and Humans are good at parenting.
Human beings apply infinitely more care (ATTENTION) to their offspring than any animal because:
-humans are more mentally complex than animals. When they look after their offspring, they do it smarter than an animal.
-humans are more emotionally and socially complex than animals. They have a complex social system, they do it with more emotional depth.
-has to teach them language and pretty much everything about the world (animals can't do this because they don't understand the world)
-teaches them specialised skills like writing, numeracy, sports, social etiquette (complex skills can't even be understood by animals)
-feeds, clothes them. worries about their diet, skin, friends, education, finances and love life. (most animals do not stay in contact with their children into old age, for example)
So first off, do you mean all animals? Because I'm comparing humans to the smartest non-humans. Like elephants. Or dolphins, or chimps, or orcas, or crows, or what-have-you. Second, mentally complex=/= smarter. Chimps beat humans in terms of being able to figure out optimal game-theoretic strategies and use them. Humans overthink it. We apply biases and prejudices and ideas of how we'll stand socially to everything.
Third, while we quite easily have the most complex social behaviors, that's not least because we have the largest groups. That doesn't automatically translate to more emotional depth. How would you measure that, anyway? Expose an elephant to pictures of mutilated elephants and see whether they try and trample you?
Fourth, AHAHAHAHAHAHAHAHAHAHA Sorry no that's a bad argument strategy (the laughing bit). But seriously, that's false, first off (humans are quite capable of learning without a parent, they just do worse off with most other bits like being able to get enough food 'n shit), saying language automatically makes us more family-oriented is a really odd way to put it, and family orientation (at all) rather than tribal orientation is a really recent thing, like 10,000 years or so at the very most, and still isn't always the case.
Fifth, animals have quite complex skills. Oh, I'm sorry, you don't consider hunting a complex skill? Or pack dynamics? Codifying everything doesn't make us smarter.
Sixth, animals do in fact worry about their offspring when they are animals that care about their offspring, and particularly when they are herd/pack animals like humans. Elephants hold goddamn funerals. Saying that humans are smarter because we have finances is meaningless. This also doesn't apply to all humans, even.
Seventh, it takes a village to raise a child, and before agriculture, the whole tribe helped. Not just family. Everyone helped with the kids. Just like other species. Humans are unique because of tool use+high intelligence, not unique for high intelligence alone. Elephants and dolphins are smart, they just lack hands.