Because we humans are an innately social species.
Very few of us have the skills to be able to survive entirely alone.

To the extent that we must work and/or with others, our success and happiness in life
depends more on our capacities for empathy and emotional intelligence,
and our communication and relationship skills
than any other set of traits.

Fortunately, most of these things are learnable if we make the right efforts.

Why are they important , well let's see . Two imperfect people come together and they both know it . They love each other .

Because ,have you ever tried to talk to an inanimate object ? It's not fun

They aren't

Humans are social creatures. 🤷

Because lonely life isn't as easy as one might suppose after living in our screwed up society.